Glycemic effect of post-meal walking compared to one prandial insulin injection in type 2 diabetic patients treated with basal insulin: A randomized controlled cross-over study.

Studies demonstrate that post-meal walking decreases postprandial hyperglycemia in type 2 diabetic patients but it has never been tested with the active treatment comparator. The objective of this study was to determine the effect of post-meal walking on glycemic control compared with one prandial insulin in type 2 diabetic patients who failed basal insulin. A randomized controlled cross-over study of post-meal walking or one prandial insulin was done in type 2 diabetic patients who were being treated with basal insulin between May 2017 and March 2018. In post-meal walking group, patients walked after meal for 15-20 minutes one meal a day every day for 6 weeks. In prandial insulin (basal plus) group, one prandial insulin was injected before breakfast or main meal with rapid-acting insulin. The primary outcome was a difference in HbA1c reduction in post-meal walking compared with basal plus groups. Fourteen patients completed the study. By intention-to-treat analysis, HbA1c was reduced by -0.05(range:-1.08 to 0.74) and -0.19(range:-0.8 to 0.56) % in post-meal walking and basal plus groups respectively. By per-protocol analysis, post-meal walking and basal plus groups decreased HbA1c by 0.13(range:-0.74 to 1.08) and 0.2(range:-0.56 to 0.8) %, respectively. There was were no significant differences in HbA1c reduction from baseline in each group and between groups in both intention-to-treat and per-protocol analysis. Fructosamine levels were decreased by 17.5(-59 to 43) and 10(-15 to 40) μmol/L, respectively at 3 and 6 weeks in post-meal walking group whereas the respective changes in basal plus group were 12.5(-17 to 64) and 17.5(-28 to 38) μmol/L and there were no significant differences in fructosamine reduction from baseline in each group and between groups. In conclusion, although post-meal walking might be as effective as one prandial insulin to improve glycemic control in type 2 diabetic patients who failed basal insulin but the magnitude of reduction was small. A longer-term study with a larger sample size or with a different walking protocol is required.

RCT Entities:   Population Interventions Outcomes

Introduction

Several diabetes guidelines [1, 2] recommend initiation of basal insulin in type 2 diabetic patients after failure to oral hypoglycemic drugs (OHD). If fasting plasma glucose (FPG) is lowered to appropriate ranges but HbA1c has not reached the target, adding medications to reduce the postprandial hyperglycemia is the next step. Adding rapid-acting insulin before one main meal (basal-plus) or GLP-1 agonist in combination with basal insulin or switching from basal to pre-mixed insulin are the options. However, with all of the above options, the patients need more than one injection a day and may expose to increased risk of hypoglycemia. Moreover, GLP-1 agonist is expensive and has irritable gastrointestinal adverse effects.

Increased physical activity is recommended as the mainstay therapy for type 2 diabetic patients especially those who are overweight or obese [3, 4]. Recent studies demonstrate that increased physical activity by walking after meal (post-meal walking) for 10–20 minutes can reduce postprandial plasma glucose (PPG) better than walking before meal [5-12]. Colberg et al [12] showed that post-dinner walking in type 2 diabetic subjects decreased PPG at 1 hour after meal about 40 mg/dl compared with those without. Pahra et al [8] and Reynolds et al [9] respectively demonstrated that HbA1c and glycated albumin were reduced with 10–15 minutes walking after three main meals for two and eight weeks. The effect on PPG reduction has been observed since first time of walking and is not insulin dependent [10]. Nevertheless, none of the previous studies compares PPG-lowering effect of post-meal walking with that of the active comparators.

This study aimed to compare the efficacy of post-meal walking with one prandial insulin on glycemic control in type 2 diabetic patients who failed basal insulin therapy.

Material and methods

Study participants

Type 2 diabetic patients aged 35–70 years who were treated with at least one OHD and basal insulin (NPH or Determir or Glargine or Degludec) were recruited from outpatient clinics at Ramathibodi hospital. Patients who had FPG less than 150 mg/dl and HbA1c levels between 7–9% were included. The exclusion criteria were uncontrolled hypertension (systolic blood pressure > 160 or diastolic blood pressure > 100 mmHg), recent myocardial infarction or ischemic stroke within 3 months, chronic lung diseases or heart failure, foot problems (severe diabetic neuropathy, fracture, deformity, previous amputation) which were obstacle to walking, currently took systemic steroids, alcohol consumption more than 7 drinks per week or caffeine consumption more than 400 mg/day, travel regularly across time zone or perform shift work. All participants gave written informed consent. The protocol was approved by the Ethical Clearance Committee, Faculty of Medicine, Ramathibodi hospital, Mahidol university and was registered with Thai Clinical Trials Registry (TCTR20170419003) which is one of the World Health Organization’s International Clinical Trials Registry platform. The study conformed to the provisions of the Declaration of Helsinki.

Study protocol

The study was a randomized controlled cross-over study conducted between May 2017 and March 2018 at outpatient clinic, Ramathibodi hospital, Bangkok, Thailand. The study comprised of 2 weeks of run-in, 6 weeks of interventions and 2 weeks of wash-out periods prior to cross over (S1 Fig). The study protocol can be followed by the link https://doi.org/10.17504/protocols.io.72chqaw.

Run-in period

At the 1st visit of run-in period, the participants received and were instructed how to use glucose meter (Freestyle Optium H, Abbot, USA), and accelerometer (Triaxial accelerometer, Fitbit zip, Fitbit, USA). This accelerometer device has been validated for its accuracy in several trials [13-17]. Diabetes education which included insulin injection, detection and correction of hypoglycemia, self-monitoring blood glucose (SMBG), and diet and food choices were provided to all participants. Those food choices included serving and portion size as well as the compositions of nutrients.

During the 1st week of run-in period, the participants recorded the diet in food diary and performed SMBG 6 times for one day (before and 2 hours after breakfast, lunch and dinner). The participants also carried the accelerometer during the day to monitor the steps. In the 2nd week, the participants revisited our clinic to review the food diary and glucose meter use. In this week, participants must walk for 15–20 minutes at least one meal per day. The walk should be started 15–30 minutes after meal. The accelerometer was carried during the day to confirm the walking steps after meal.

Randomization

At the end of the run-in period, participants were randomized into the post-meal walking or the basal plus groups by computerized generated block of 4 randomization using program stata version 15.1. OS enrolled and assigned participants to each intervention.

The post meal walking group

The participants must walk for 15–20 minutes after meal at least one meal per day every day. The speed of walk should be “Walk as fast as possible”. During the day, the accelerometer was used to monitor the number of walking steps.

The basal plus group

The participants were advised to use rapid acting insulin analog (Glulisine, Sanofi, France) within 15 minutes before the main meal as prandial or bolus insulin. The starting dose was 4 units/meal or 0.1 unit/kg body weight depending on participants’ characteristic. Bolus insulin dose was adjusted as appropriate via mobile phone or line application within 2 weeks until 2-hour PPG ≤ 180 mg/dl. In this group, the participants could do their usual activity but they were advised not to walk after meal.

During the study period, if the participants developed hyperglycemic emergency (diabetic ketoacidosis, hyperglycemic hyperosmolar state), had FPG > 250 mg/dl or HbA1c > 9%, the participants would be excluded from the study.

Measurements

In one day of each week, the participants of both groups recorded the food diary and performed SMBG 6 times a day (before and 2 hours after breakfast, lunch and dinner). The participants continued their usual doses of OHD and basal insulin. If there was evidence of hypoglycemic event, the physicians would adjust the regimen as appropriate.

The participants visited the clinic at 0, 3, and 6 weeks of each intervention to have blood tests, reviewed the food diary, SMBG records, accelerometer use and self-care.

Blood samples were measured in the central laboratory of Ramathibodi hospital in the same day of the tests. Plasma glucose was measured by Hexokinase/Glucose-6-Phosphate Dehydrogenase method (Abbot, USA). HbA1c was measured by turbidimetric inhibition immunoassay (Roche, Germany). Fructosamine was measured by chemiluminescence method (Roche, Germany).

Outcomes

The primary outcome was a difference in HbA1c reduction from baseline between basal plus and post-meal walking groups. The hypothesis was that HbA1c reduction between two groups was not different. The main secondary outcome was a difference of fructosamine reduction from baseline between groups.

Statistical analysis

The sample size was calculated using the formula: The number of participants required to detect a 0.5% HbA1c difference was calculated. A paired-tests with an alternative hypothesis mean of 0.5 and a standard deviation of 0.65 requires a sample size of 14 to attain 80% power, assuming a two-sided alpha of 0.05. Estimation of HbA1c variation with 0.65% standard deviation was used according to previous study from Lankisch et al [18]. Assuming there would be 15% dropout rate, we designed to include 16 participants into the study. The analysis was based on statistical concept of the cross-over study. Multilevel mixed-effects linear regression was used for analysis of the normal distribution outcomes, a fixed effect model with treatment, sequence and period entered into the model and subjects was a random effect. The median regression analysis was used for the non-normal distribution outcomes. All data was analyzed by the STATA program version 15.

Results

Nineteen participants were recruited between May 2017 and March 2018 but five withdrew from the study during run-in period (S1 Fig). The baseline characteristics of 14 participants were shown in Tables 1 and S1. About two-third of participants used insulin glargine as a basal insulin. Sulfonylurea (85%), metformin (71%) and dipeptidyl peptidase 4 inhibitors (50%) were the main OHD in this study. Pioglitazone, sodium-glucose co-transporter 2 inhibitors and alpha-glucosidase inhibitors were used in four (28.6%), two (14.3%) and one (7.1%) participants, respectively.

Table 1

Baseline characteristics of participants.

Baseline characteristics (N = 14)a
Female	8 (57.1%)
Age (years)	56.93 ± 1.82
Weight (kg)	77.29 ± 5.48
BMI (kg/m2)	29.45 ± 1.66
Waist circumference (cm)	99.43 ± 3.92
Duration of diabetes (years)	9 (1–22)
HbA1c (%)	7.90 ± 0.12
Fasting plasma glucose (mg/dl)	131.29 ± 6.94
Dose of basal insulin (units)	16 (6–44)
Numbers of oral hypoglycemic drugs	2.5 ± 0.23

a Data are expressed as mean ± SE or median (range)

The participants in post-meal walking group had significantly greater total daily steps, total post-meal walking steps and time spending in post-meal walking after lunch and dinner than those in basal plus group. Most of participants in post-meal walking group walked after dinner. None of participants in basal plus group walked after meals. Concerning bolus insulin, eight participants used bolus insulin at breakfast, five at dinner and one at lunch. Both total carbohydrates and caloric intake per day of post-meal walking group were significantly greater than those of basal plus group particularly at lunch time (S2 Table).

As shown in Fig 1, by intention-to-treat analysis, HbA1c was reduced by -0.05 (range: -1.08 to 0.74) and -0.19 (range:-0.8 to 0.56) % in post-meal walking and basal plus groups respectively. However, by per-protocol analysis, the respective reduction in HbA1c was -0.13 (range: -0.74 to 1.08) and -0.20 (range: -0.56 to 0.8) %. There were no significant differences of HbA1c reduction from baseline in each group and between groups in both intention-to-treat and per-protocol analysis. In post-meal walking group, fructosamine levels was decreased from baseline at 3 and 6 weeks whereas in basal plus group, it was decreased only at 3 week. However, the magnitude of the overall fructosamine reduction from baseline was not different in each group and between groups. (Fig 2)

Fig 1

Changes of HbA1c levels of the post-meal walking and basal plus groups by intention-to-treat analysis.

Δ HbA1c is expressed as median (range).

Fig 2

Changes of serum fructosamine levels in post-meal walking and basal plus groups.

Data are expressed as mean ± SE.

The glucose excursion of SMBG at 3 and 6 weeks were decreased from baseline in both groups but did not reach statistical significance (S2 and S3 Figs). Few episodes of documented hypoglycemic events (glucose <70 mg/dl) occurred in two participants. There was no other adverse events in each group.

Discussion

Our results indicated that in patients with type 2 diabetes who were being treated with basal insulin, the HbA1c reduction by post-meal walking or one prandial insulin injection were not different at 6 weeks. Shorter term glycemic control as indicated by fructosamine levels was improved by post-meal walking group but was not significantly different from baseline and was not different from that of basal plus group. Therefore, post-meal walking may be as effective as one prandial insulin in control of PPG in type 2 diabetic patients who fail from basal insulin at least in short-term basis. To our knowledge, this was the first study that evaluated the role of post-meal walking on PPG control compared with standard prandial insulin therapy in free-living diabetic patients.

However, it should be noted that HbA1c reduction at 6 weeks of post-meal walking group was quite small. There are several plausible reasons to explain this unexpected finding. First, 15 min of walking after one meal in this study may not be long enough for meaningful reduction of PPG. The study by Van Dijk et al [11] demonstrated that walking after meal for 15 min although could reduce PPG in type 2 diabetic patients, but the reduction did not reach statistical significance. In other studies, at least 20 minutes of walking after one meal or 10–15 minutes per each meal everyday demonstrated significant glycemic reduction [8, 9, 12, 19]. Pahra et.al [8] demonstrated that post-meal walking for 1,500–1,600 steps for 15 min after three main meals could significantly decrease the HbA1c levels of 0.9% at 8th weeks. In our study, the post-meal walking steps after dinner which was the main meal of walking was only 700 steps. These indicate that the amount of steps and times spending in post-meal walking of our study may be inadequate. Second, patients assigned for post-meal walking in our study may not comply with the walking protocol. It could be noted from S2 and S3 Tables that some patients did not walk after meal. As seen from Fig 1, five of 14 participants had increasing HbA1c levels after 6-week of post-meal walking. Of these five, three did not comply with walking protocol. Therefore, the efficacy of post-meal walking in terms of HbA1c reduction may be underestimated. If we used per-protocol analyses and excluded these three participants, there would be 0.13 and 0.20% reduction of HbA1c in post-meal walking and basal plus group, respectively. It could have been possible that if our subjects were strict to walking protocol, the magnitude of HbA1c reduction in post-meal walking group would be greater. Third, time and the amount of meal at which walking is performed is also an important issue. Several studies performed walking after breakfast [5-7], of which maximum glucose excursion occurred [20]. A study by Reynold et al [9] showed that walking after meal with the most substantial amount of carbohydrate, could decrease PPG more effectively than walking after other meals. Since most participants walked after dinner and dinner was not a main meal in our study (S2 Table), the magnitude of PPG reduction with post-meal walking may be substantially under-estimated. Fourth, given the daily total carbohydrate and caloric intake of post-meal walking group were significantly greater than those of basal plus group, the effect of walking on HbA1c reduction may also be under-estimated. It should be noted that the magnitude of HbA1c reduction was also modest in basal plus group as compared with other previous studies [18, 21]. This may be due to a shorter time of treatment compared with other studies.

Our study had several limitations. First, we used 6 points blood glucose monitoring data from once weekly SMBG which might not be adequate to represent a real, daily blood glucose fluctuation. Second, the duration of the study was not long enough to capture the exact changes of HbA1c levels. However, we tried to solve this problem by using fructosamine levels. Furthermore, the study results may be influenced by carry over effects due to the short intervention and wash-out periods chosen. However, there was no difference of HbA1c at the end (6th week) of first intervention and at the start (0 week) of the second intervention groups (HbA1c 7.51 vs 7.53%, P = 0.878) in participants who started with post-meal walking and in those who started with basal plus (HbA1c 7.27 vs 7.30%, P = 0.885). Third, the sample size in this study was small. A significant number of our participants did not comply with the walking protocol. The strengths of this study were that it was the first and the longest study that compared post-meal walking with prandial insulin in basal insulin treated type 2 diabetic patients with valid study design. Most previous studies were performed in the controlled, experimental conditions and had no active treatment as a comparator.

Conclusion

This study indicated that post-meal walking of at least one meal per day might be as efficient as one mealtime insulin to improve glycemic control in type 2 diabetic patients who failed from basal insulin therapy. Nevertheless the magnitude of glycemic reduction appears to be small. A longer-term study with a larger sample size and/or with a different walking protocol is required to test the efficiency and effectiveness of post-meal walking in glycemic control of type 2 diabetic patients in real world.

Baseline characteristics of each participant in the study.

(DOCX)

Click here for additional data file.

Dietary intake, walking steps and time spending in walking in post-meal walking and basal plus groups.

(DOCX)

Click here for additional data file.

Insulin dosages, post-meal walking steps and duration and plasma glucose levels changes by prandial insulin or post-meal walking of each participant in the study.

(DOCX)

Click here for additional data file.

The study protocol.

(TIF)

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Self-monitoring blood glucose results of post-meal walking group.

(TIF)

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Self-monitoring blood glucose results of basal plus group.

(TIF)

Click here for additional data file.

CONSORT 2010 checklist.

(PDF)

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Study protocol-Thai version.

(PDF)

Click here for additional data file.

Study protocol-English translation.

(PDF)

Click here for additional data file.

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20 Sep 2019

PONE-D-19-20612

Glycemic effect of post-meal walking compared to one prandial insulin injection in type 2 diabetic patients treated with basal insulin: a randomized controlled cross-over study”

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Reviewer #1: This is an interesting study comparing the effects of prandial insulin with post-prandial walking. Anything that encourages exercise ahead of insulin should be encouraged.

I think that we should regard this as a pilot study which requires further work and hopefully publication will stimulate this.

However:

• The study was only over a very short period. HbA1c will not have had time to change as significantly as it could have over say 12 weeks.

• This was a group of patients were on a variety of OHDs – I realise that they were controls against themselves but I am surprised that some patients remained on sulphonylureas. I assume that the basal insulin (type and dosage) remained the same for both legs.

• Only 14 out of 19 completed the study. Within these groups some in the walking post-meal group did not walk and is there any guarantee that in the group that had the prandial insulin that they did not walk post meal?

• 700 steps is not very far and I suspect rather than aiming for “Walk as fast as possible” setting a target of possibly 1000 or 1500 steps would have been better.

• I am not sure why the time that patients were asked to walk was not after the same meal that they were going to take their prandial insulin – surely that would have been a better comparison?

• I may have missed this - did any of the patients develop DKA or HHS?

• Only fructosamine and HbA1c were measured. Lipids, BP, weight etc would have been useful. Particularly a Q of L questionnaire would have been interesting to see if patients preferred the walking or the prandial insulin.

• It would have better if the groups could have been controlled for calorific intake. Eating more at lunch in the walking group will have diluted the results.

Reviewer #2: The authors adress whether post-meal walking may be as effective to lower HbA1c as once daily prandial insulin administerd before the main/largest meal in patients with type 2 DM and inadequate glycemic control (A1c > 7.0%) despite treatment with oral hypoglycemic drugs and basal insulin. A cross-over design with two six weeks treatment periods and a 2 weeks washout period is empoyed. A mixed model is employed to test for significance between the two treatment types/periods.

Major concerns:

Although the authors adress an important and relevant question, the study design is flawed by the duration of the study periods and the primary endpoint (A1c) chosen. The authors acknowledge that their design with 6 weeks treatment periods and a 2 weeks washout-period carries a significant risk of carry-over effects. The discussed fact, that the A1c did not change during the washout period it is not helpful at all since even significant changes in glycemic excursions are unlikely to change A1c concentrations within this short time period. Since the authors seem to be aware of this, either a different primary endpoint or a different study design should have been chosen.

Minor concerns:

Statistical analysis: the details of the the mixed model (i.e. parameters chosen for fixed, random effects, period, etc.) should be indicated in order to make the analysis plan reproducible.

The patients were instructed to use prandial insulin before the main meal (basal plus period) or to briskly walk after at least one meal (post-meal walking period). To judge the comparative effects of the 2 interventions compareable time periods should be analyzed. I.e., if prandial insulin was given before dinner, this period should also be looked at in the post meal walking group and data should be presented accordingly.

Detailed data regarding the insulin therapy should be indicated (i.e. dose, time-course of dose escalation) should be indicated in order to judge whether appropriate dose adjustments were made.

The caloric intake in the basal plus group was significantly lower. Can the authors offer an explanation for this finding ?

Some english language editing is adviseable.

The individual participant data used for the final analysis should be made available.

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Reviewer #1: Yes: Prof Andrew Collier

Reviewer #2: No

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8 Oct 2019

Responses to reviewer #1

1. The study was only over a very short period. HbA1c will not have had time to change as significantly as it could have over say 12 weeks.

Answer: It is well known that HbA1c is an estimate of mean plasma glucose levels in the previous 3-4 months, however 50% of the result is from mean plasma glucose level 0-30 days or 1 month prior to blood sampling (Can J Diabetes 2013; 37: S35-S39). Therefore we believe 6-week of intervention should have significant change (if any) to HbA1c results. We’re afraid that if the intervention of interest (post-meal walking) is continued for 12 weeks to capture all changes of HbA1c, the participants might not cooperate and we might have lost some of the participating subjects during the trial.

2. This was a group of patients were on a variety of OHDs – I realise that they were controls against themselves but I am surprised that some patients remained on sulphonylureas. I assume that the basal insulin (type and dosage) remained the same for both legs.

Answer: It is a common practice in Thailand that sulphonylureas is not withdrawn while being on basal insulin. As shown in the S3 table, basal insulin type was not changed. Basal insulin dosage was stable in all except two subjects in each arm, the dosage was minimally reduced due to mild hypoglycemia.

3. Only 14 out of 19 completed the study. Within these groups some in the walking post-meal group did not walk and is there any guarantee that in the group that had the prandial insulin that they did not walk post meal?

Answer: Since all participants carried accelerometers during the trial, we could monitor whether they walked after prandial insulin injection or not. It was shown that none of the participants in the basal plus arm violated the protocol. We have added this statement in the Results.

4. 700 steps is not very far and I suspect rather than aiming for “Walk as fast as possible” setting a target of possibly 1000 or 1500 steps would have been better.

Answer: We absolutely agree with you. The greater the number of post-meal steps, the lower of post-meal glucose levels is anticipated but in real life, walking for 1,000-1,500 steps post-meal might not be practical for some patients particularly with elderly patients. We try to make our protocol feasible and practical. However, we re-analyzed individual data of each participant and found that those who complied with the walking protocol, the averaged post-meal walking steps was in fact more than 1,000 steps as shown in S3 Table.

5. I am not sure why the time that patients were asked to walk was not after the same meal that they were going to take their prandial insulin – surely that would have been a better comparison?

Answer: We absolutely agree with this comment but in real life, the free time that patients have to spend on walking does not always get along with the main meal. As having been said, we try to make it practical.

6. I may have missed this - did any of the patients develop DKA or HHS?

Answer: None of the participants developed hyperglycemic emergencies during the trial

7. Only fructosamine and HbA1c were measured. Lipids, BP, weight etc would have been useful. Particularly a Q of L questionnaire would have been interesting to see if patients preferred the walking or the prandial insulin.

Answer: Unfortunately we did not collect those data

8. It would have better if the groups could have been controlled for calorific intake. Eating more at lunch in the walking group will have diluted the results.

Answer: We agree but unlike in clinical research environment, controlling for caloric intake in free living condition is difficult and make the study protocol more complicated

Responses to reviewer#2

Major concerns:

Although the authors address an important and relevant question, the study design is flawed by the duration of the study periods and the primary endpoint (A1c) chosen. The authors acknowledge that their design with 6 weeks treatment periods and a 2 weeks washout-period carries a significant risk of carry-over effects. The discussed fact, that the A1c did not change during the washout period it is not helpful at all since even significant changes in glycemic excursions are unlikely to change A1c concentrations within this short time period. Since the authors seem to be aware of this, either a different primary endpoint or a different study design should have been chosen.

Answer: As similar to our responses to reviewer#1, we believe 6-week of intervention should have significant change to HbA1c results since half of A1c change would occur in the first 30 days prior to blood sampling although it cannot capture all changes (Can J Diabetes 2013; 37: S35-S39). Fructosamine level which can reflect the shorter term changes of mean plasma glucose levels may be a better choice in this regard but since its measurement method is not well standardized and it is not a standard measure of glucose control in clinical practice, therefore we decide to use fructosamine as a secondary endpoint of the study.

Minor concern

1. Statistical analysis: the details of the the mixed model (i.e. parameters chosen for fixed, random effects, period, etc.) should be indicated in order to make the analysis plan reproducible.

Answer: The details of the mixed model statistical analysis were added in the manuscript as suggested

2. The patients were instructed to use prandial insulin before the main meal (basal plus period) or to briskly walk after at least one meal (post-meal walking period). To judge the comparative effects of the 2 interventions comparable time periods should be analyzed. I.e., if prandial insulin was given before dinner, this period should also be looked at in the post meal walking group and data should be presented accordingly.

Answer: As you can see in the S3 Table, the meals at which the patients walked or injected prandial insulin were not always the same, therefore it is impossible to analyze such data. We designed our protocol to be practical in real life, so we did not fix the meal at which post-meal walking was performed.

3. Detailed data regarding the insulin therapy should be indicated (i.e. dose, time-course of dose escalation) should be indicated in order to judge whether appropriate dose adjustments were made.

Answer: Insulin dose and changes of plasma glucose levels post-meal by walking or prandial insulin were demonstrated in S3 Table

4. The caloric intake in the basal plus group was significantly lower. Can the authors offer an explanation for this finding?

Answer: This finding may occur by chance since we did not control the caloric intake of the participants during the trial.

5. The individual participant data used for the final analysis should be made available.

Answer: The individual participant data was shown in S3 Table

Other inquiries

Please include a copy of Table 2 which you refer to in your text on page 11.

Answer: It is a mistake, Table 2 is actually a S2 Table. This has been corrected in the revised manuscript.

Please note that we have corrected some mistake in the abstract (line 33 page 2).

The study protocol has been deposited to protocol io and its DOI has been added in the manuscript as recommended.

Submitted filename: Responses to reviewers letter.docx

Click here for additional data file.

28 Jan 2020

PONE-D-19-20612R1

Glycemic effect of post-meal walking compared to one prandial insulin injection in type 2 diabetic patients treated with basal insulin: a randomized controlled cross-over study”

PLOS ONE

Dear Professor Rattarasarn,

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Academic Editor

PLOS ONE

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Reviewers' comments:

Reviewer's Responses to Questions

Comments to the Author

1. If the authors have adequately addressed your comments raised in a previous round of review and you feel that this manuscript is now acceptable for publication, you may indicate that here to bypass the “Comments to the Author” section, enter your conflict of interest statement in the “Confidential to Editor” section, and submit your "Accept" recommendation.

Reviewer #1: All comments have been addressed

Reviewer #2: All comments have been addressed

Reviewer #3: (No Response)

**********

2. Is the manuscript technically sound, and do the data support the conclusions?

The manuscript must describe a technically sound piece of scientific research with data that supports the conclusions. Experiments must have been conducted rigorously, with appropriate controls, replication, and sample sizes. The conclusions must be drawn appropriately based on the data presented.

Reviewer #1: Yes

Reviewer #2: Yes

Reviewer #3: Yes

**********

3. Has the statistical analysis been performed appropriately and rigorously?

Reviewer #1: Yes

Reviewer #2: Yes

Reviewer #3: Yes

**********

4. Have the authors made all data underlying the findings in their manuscript fully available?

The PLOS Data policy requires authors to make all data underlying the findings described in their manuscript fully available without restriction, with rare exception (please refer to the Data Availability Statement in the manuscript PDF file). The data should be provided as part of the manuscript or its supporting information, or deposited to a public repository. For example, in addition to summary statistics, the data points behind means, medians and variance measures should be available. If there are restrictions on publicly sharing data—e.g. participant privacy or use of data from a third party—those must be specified.

Reviewer #1: Yes

Reviewer #2: Yes

Reviewer #3: Yes

**********

5. Is the manuscript presented in an intelligible fashion and written in standard English?

PLOS ONE does not copyedit accepted manuscripts, so the language in submitted articles must be clear, correct, and unambiguous. Any typographical or grammatical errors should be corrected at revision, so please note any specific errors here.

Reviewer #1: Yes

Reviewer #2: Yes

Reviewer #3: Yes

**********

6. Review Comments to the Author

Please use the space provided to explain your answers to the questions above. You may also include additional comments for the author, including concerns about dual publication, research ethics, or publication ethics. (Please upload your review as an attachment if it exceeds 20,000 characters)

Reviewer #1: The concept of exercise in place of insulin is an interesting and useful one.

This should be regarded as a pilot and encourage others to undertake further work.

There are faults with the design in this study but cannot be changed now.

The authors answer all the points made by the reviewers.

Reviewer #2: Although the authors acknowledge the major concerns of the reviewers in their response letter no appropriate changes have been made to the manuscript. The authors should clearly state in their conclusion that the study results may be influenced by carry over effects due to the short inntervention and wash-out periods Chosen.

Reviewer #3: A randomized controlled cross-over study was conducted in patients (n=14) with type 2 diabetes with the goal of determining the effect of post-meal walking on glycemic levels compared to prandial insulin. The change in HbA1c was the primary outcome. There were no significant differences in HbA1c from baseline to follow-up in with or between the groups.

Minor revisions:

1- Abstract: Please clarify the following statement since both confidence intervals contain zero.It seems reasonable that neither group showed a statistically significantly decrease over baseline.

“By per-protocol analysis, post-meal walking and basal-plus groups significantly decreased HbA1c by 0.13(range:-0.74 to 1.08) and 0.26(range:-0.8 to 0.08) %, respectively.”

2- Line 145: Indicate if the alpha level was one- or two-sided. The beta for a power of 0.80 is 0.20. Please clarify.

3- Line 146: This statement is technically incorrect. “At least 14 participants were needed to demonstrate the statistical significance.” Possibly something to this effect would be more appropriate, “A paired-tests with an alternative hypothesis mean of 0.5 and a standard deviation of 0.65 requires a sample size of 14 to attain 80% power, assuming a two-sided alpha of 0.05.” Possibly this test should be one-sided since a decrease in HbA1c is expected.

4- Line 149: Indicate the underlying covariance structure used in the linear mixed models and the criteria for choosing it.

5- Line 189-191: Provide the overall p-value for comparing times 0, 3 and 6. If the overall p-value is significant use a multiple comparison tests to summarize pairwise differences.

6- Both Figures 1 and 2 display nearly identical data. Include only one of these.

**********

7. PLOS authors have the option to publish the peer review history of their article (what does this mean?). If published, this will include your full peer review and any attached files.

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Reviewer #1: No

Reviewer #2: Yes: Stefan Bilz

Reviewer #3: No

[NOTE: If reviewer comments were submitted as an attachment file, they will be attached to this email and accessible via the submission site. Please log into your account, locate the manuscript record, and check for the action link "View Attachments". If this link does not appear, there are no attachment files to be viewed.]

While revising your submission, please upload your figure files to the Preflight Analysis and Conversion Engine (PACE) digital diagnostic tool, https://pacev2.apexcovantage.com/. PACE helps ensure that figures meet PLOS requirements. To use PACE, you must first register as a user. Registration is free. Then, login and navigate to the UPLOAD tab, where you will find detailed instructions on how to use the tool. If you encounter any issues or have any questions when using PACE, please email us at figures@plos.org. Please note that Supporting Information files do not need this step.

12 Feb 2020

Responses to reviewer #1. The concept of exercise in place of insulin is an interesting and useful one. This should be regarded as a pilot and encourage others to undertake further work. There are faults with the design in this study but cannot be changed now.

The authors answer all the points made by the reviewers.

Answer: No specific query raised by the reviewer.

Responses to reviewer#2. Although the authors acknowledge the major concerns of the reviewers in their response letter no appropriate changes have been made to the manuscript. The authors should clearly state in their conclusion that the study results may be influenced by carry over effects due to the short intervention and wash-out periods chosen.

Answer: We have addressed the concerning issue raised by reviewer #2 in the Discussion part.

Responses to reviewer#3.

1. Abstract: Please clarify the following statement since both confidence intervals contain zero. It seems reasonable that neither group showed a statistically significantly decrease over baseline.

“By per-protocol analysis, post-meal walking and basal-plus groups significantly decreased HbA1c by 0.13(range:-0.74 to 1.08) and 0.26(range:-0.8 to 0.08) %, respectively.”

Answer: This statement has actually been corrected in the first revised manuscript but may have been missed. The statement that has already been in the Abstract is “There was no significant differences in HbA1c reduction from baseline in each group and between groups in both intention-to-treat and per-protocol analysis”

2. Line 145: Indicate if the alpha level was one- or two-sided. The beta for a power of 0.80 is 0.20. Please clarify.

3. Line 146: This statement is technically incorrect. “At least 14 participants were needed to demonstrate the statistical significance.” Possibly something to this effect would be more appropriate, “A paired-tests with an alternative hypothesis mean of 0.5 and a standard deviation of 0.65 requires a sample size of 14 to attain 80% power, assuming a two-sided alpha of 0.05.” Possibly this test should be one-sided since a decrease in HbA1c is expected.

Answer: Those statements have been corrected and revised according to the reviewer’s suggestion.

4. Line 149: Indicate the underlying covariance structure used in the linear mixed models and the criteria for choosing it.

Answer: We explore data in each patient and it showed random intercept and random slope. So we decided to choose random coefficient model for our outcome analysis.

5. Line 189-191: Provide the overall p-value for comparing times 0, 3 and 6. If the overall p-value is significant use a multiple comparison tests to summarize pairwise differences.

Answer: We thank the reviewer for this suggestion. Actually there was no overall change of fructosamine levels after intervention, therefore the result of fructosamine measurements has been revised in the Result and Discussion sections. Figure of fructosamine results has also been revised accordingly.

6. Both Figures 1 and 2 display nearly identical data. Include only one of these.

Answer: Fig 2 has been removed and replaced with Fig 3.

Submitted filename: Responses to reviewers letter_2nd revision.docx

Click here for additional data file.

4 Mar 2020

Glycemic effect of post-meal walking compared to one prandial insulin injection in type 2 diabetic patients treated with basal insulin: a randomized controlled cross-over study”

PONE-D-19-20612R2

Dear Dr. Rattarasarn,

We are pleased to inform you that your manuscript has been judged scientifically suitable for publication and will be formally accepted for publication once it complies with all outstanding technical requirements.

Within one week, you will receive an e-mail containing information on the amendments required prior to publication. When all required modifications have been addressed, you will receive a formal acceptance letter and your manuscript will proceed to our production department and be scheduled for publication.

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If your institution or institutions have a press office, please notify them about your upcoming paper to enable them to help maximize its impact. If they will be preparing press materials for this manuscript, you must inform our press team as soon as possible and no later than 48 hours after receiving the formal acceptance. Your manuscript will remain under strict press embargo until 2 pm Eastern Time on the date of publication. For more information, please contact onepress@plos.org.

With kind regards,

Noël C. Barengo, MD, PhD, MPH

Academic Editor

PLOS ONE

Additional Editor Comments (optional):

Reviewers' comments:

Reviewer's Responses to Questions

Comments to the Author

1. If the authors have adequately addressed your comments raised in a previous round of review and you feel that this manuscript is now acceptable for publication, you may indicate that here to bypass the “Comments to the Author” section, enter your conflict of interest statement in the “Confidential to Editor” section, and submit your "Accept" recommendation.

Reviewer #2: All comments have been addressed

Reviewer #3: All comments have been addressed

**********

2. Is the manuscript technically sound, and do the data support the conclusions?

The manuscript must describe a technically sound piece of scientific research with data that supports the conclusions. Experiments must have been conducted rigorously, with appropriate controls, replication, and sample sizes. The conclusions must be drawn appropriately based on the data presented.

Reviewer #2: Yes

Reviewer #3: (No Response)

**********

3. Has the statistical analysis been performed appropriately and rigorously?

Reviewer #2: Yes

Reviewer #3: (No Response)

**********

4. Have the authors made all data underlying the findings in their manuscript fully available?

The PLOS Data policy requires authors to make all data underlying the findings described in their manuscript fully available without restriction, with rare exception (please refer to the Data Availability Statement in the manuscript PDF file). The data should be provided as part of the manuscript or its supporting information, or deposited to a public repository. For example, in addition to summary statistics, the data points behind means, medians and variance measures should be available. If there are restrictions on publicly sharing data—e.g. participant privacy or use of data from a third party—those must be specified.

Reviewer #2: Yes

Reviewer #3: (No Response)

**********

5. Is the manuscript presented in an intelligible fashion and written in standard English?

PLOS ONE does not copyedit accepted manuscripts, so the language in submitted articles must be clear, correct, and unambiguous. Any typographical or grammatical errors should be corrected at revision, so please note any specific errors here.

Reviewer #2: Yes

Reviewer #3: (No Response)

**********

6. Review Comments to the Author

Please use the space provided to explain your answers to the questions above. You may also include additional comments for the author, including concerns about dual publication, research ethics, or publication ethics. (Please upload your review as an attachment if it exceeds 20,000 characters)

Reviewer #2: (No Response)

Reviewer #3: (No Response)

**********

7. PLOS authors have the option to publish the peer review history of their article (what does this mean?). If published, this will include your full peer review and any attached files.

If you choose “no”, your identity will remain anonymous but your review may still be made public.

Do you want your identity to be public for this peer review? For information about this choice, including consent withdrawal, please see our Privacy Policy.

Reviewer #2: Yes: Stefan Bilz

Reviewer #3: No

11 Mar 2020

PONE-D-19-20612R2

Glycemic effect of post-meal walking compared to one prandial insulin injection in type 2 diabetic patients treated with basal insulin: a randomized controlled cross-over study”

Dear Dr. Rattarasarn:

I am pleased to inform you that your manuscript has been deemed suitable for publication in PLOS ONE. Congratulations! Your manuscript is now with our production department.

If your institution or institutions have a press office, please notify them about your upcoming paper at this point, to enable them to help maximize its impact. If they will be preparing press materials for this manuscript, please inform our press team within the next 48 hours. Your manuscript will remain under strict press embargo until 2 pm Eastern Time on the date of publication. For more information please contact onepress@plos.org.

For any other questions or concerns, please email plosone@plos.org.

Thank you for submitting your work to PLOS ONE.

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on behalf of

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PLOS ONE