Correlation between Diabetic Retinopathy and Diabetic Peripheral Neuropathy in Patients with Type II Diabetes Mellitus.

Background and
Objectives: The two most common complications of diabetes mellitus are retinopathy and neuropathy which are dealt by two different medical departments. Early detection and management are therefore necessary to prevent progression of these two diseases and will give a knowledgeable idea regarding the both. Thus, this study was done to know the association of diabetic peripheral neuropathy and diabetic retinopathy.
Methods: This was a cross sectional study comprised of 200 cases of type 2 diabetes mellitus selected from the ophthalmology department and referred cases from other departments. A thorough history and examination was done in both departments, that is, complete ophthalmic and neurological examination respectively. Relevant investigations, if needed, were done and diabetic retinopathy was classified according to ETDRS classification.
Results: Of the 200 patients having type 2 diabetes for more than 5 years, 28% of cases had diabetic retinopathy and 59% of cases had peripheral neuropathy. Peripheral neuropathy was twice more common than retinopathy. 33.1% had retinopathy and 65.46% had peripheral neuropathy among the uncontrolled diabetics. The prevalence of retinopathy increased 1.3 times in patients with neuropathy (16%) than in patients without peripheral neuropathy (12%).
Conclusion: As there was higher incidence of peripheral neuropathy, it is important as ophthalmologists to look for peripheral neuropathy in diabetics which will help in reducing diabetes-related morbidities. Copyright:

INTRODUCTION

Diabetes mellitus (DM) is evolving as a global epidemic and its prevalence is anticipated to increase in the future. Diabetes mellitus affects more than 240 million people worldwide.[1] It is the most common non-communicable disease seen in India and is expected to affect 79.4 million by 2030.[2]

The commonest microvascular complications of diabetics are diabetic retinopathy and peripheral retinopathy.[3] Diabetic retinopathy (DR) is the most common blinding disease among adults in the West.[45] Development of diabetic retinopathy in patients with type 2 diabetes was found to be related to both severity of hyperglycemia and presence of hypertension in the United Kingdom Prospective Diabetes Study.[6]

Diabetic peripheral neuropathy (DPN) is a diagnosis of exclusion where diagnosis is made based on presence of symptoms and signs of nerve dysfunction, and is relied on duration and degree of glycemic control.[7]

In our country, because of the lack of awareness about the disease as well as poor motivation for regular health check-up, patients only come for consultation after the disease has turned symptomatic. Retinopathy and neuropathy are two different entities and are managed by two different specialists. It is difficult to refer cases to others; hence, only one mode of care is given. Thus, this cross-sectional study is being planned to study the correlation between DR and DPN among patients with type 2 DM so that an interdisciplinary approach involving physicians, ophthalmologists, and endocrinologists in the care of patients with DM may be emphasized.

AIMS AND OBJECTIVES

To study the correlation of diabetic retinopathy with diabetic peripheral neuropathy in patients with type 2 diabetes mellitus.

METHODOLOGY

The study was conducted in the department of ophthalmology for a duration of one year with cooperation from other departments. Patients in the age group of 45–75 years with a history of type 2 diabetes mellitus for more than five years, attending Ophthalmology Outpatient Department, Ophthalmology ward, and referred patients from other departments were included in the study. Patients with neuropathy and retinopathy due to other causes were excluded from the study.

Taking 34.1% prevalence of diabetic retinopathy, according to a clinic-based study conducted by Rema M et al., sample size for the study was calculated using the formula 4 pq/L.[8] The sample size came to around 200.

The statistical tools used to assess the results at the end of the study period were.

Measures of central tendency and variation used – mean, median, standard deviation

Frequency and percentage

Chi-squared test

P-value for significance

Study patients after taking consent underwent detailed ophthalmic examination and fundus mapping, and presence of diabetic retinopathy was graded according to ETDRS classification.

Presence of DPN was detected by the physician based on any history suggesting neuropathy-like tingling sensation, numbness, burning sensation, and history of non-healing foot ulcer. Following tests, vibration sensation, perception of touch, pain sensation proprioception, and ankle jerk were noted. Results were compiled and statistical analysis done.

RESULTS

In our study, all cases ranged between the age group of 45 years to 75 years. Mean age was 58.14 years with SD as 9.513, with males being 113 (56.5%) and females 87 (43.5%).

Out of 200 patients, 144 patients had no diabetic retinopathy, 28 patients (14%) had mild NPDR, 14 (7%) had moderate NPDR, 5 (2.5%) had severe NPDR, and 9 (4.5%) had PDR. None had very severe NPDR.

Out of 200 patients, we found that 118 patients (59%) had DPN with 72 patients having neuropathy with diabetic duration of 11–18 years.

Of the 200 patients, 118 patients (59%) had diminished vibration, Ankle jerk was diminished in 89 (44.5%) patients, 160 patients (80%) had no tingling sensation, and 40 (20%) had history of tingling sensation. Numbness was present in 58 patients (29%). Burning sensation was present in 20 patients (10%), whereas it was absent in 180 patients (90%).

Out of 110 patients with no family history of DM, 72 patients had neuropathy. Out of 90 patients with positive family history for diabetes, 46 had neuropathy. Statistically significant difference was noted in neuropathic patients with positive family history and without family history of diabetes (P = 0.04).

Out of 200 patients, only diabetic retinopathy cases were 7 (3.5%), only diabetic peripheral neuropathy cases were 69 (34.5%), and patients who had both were 49 (24.5%).

Prevalence of DR in patients with and without DPN were 41.5% and 8.5%, respectively. There was a statistically significant difference between the two (P = 0.000).

Out of 144 patients with no DR, 69 had neuropathy and 25 did not have neuropathy.

In mild NPDR group, 24 patients had neuropathy and 4 patients had no neuropathy (P < 0.001) In moderate NPDR group, 12 patients had neuropathy and 2 patients had no neuropathy (P < 0.001).

In severe NPDR group, 4 patients had neuropathy and 1 patient had no neuropathy (P < 0.001).

In PDR group, all 9 patients had neuropathy (P < 0.001).

DISCUSSION

In the present study, prevalence of DR was found to be 28%. Studies conducted by Virendra K Sharma et al.,[9] Zhang X et al.[10] and XuJ, Wei B et al.[11] are in agreement with our study. But some studies like those by Wong TY, Cheung N et al.[12], Jordar ND, Germain N et al.[13] found the DR prevalence higher than our study.

In our study, prevalence of DPN was 59%. In a study done by Salwa SIA et al.[14] and Katulanda P et al.[15] the prevalence rate agrees with our treatment.

Mean age in our study was 58.14 ± 9.5 years, which was in par with other studies conducted by Raman R et al.[16] and Won JC et al.[17]

Out of 56 patients with neuropathy, females were 21 (37.5%) and males were 35 (62.5%). There was male preponderance in our study. Similar male preponderance was seen in many other studies like one conducted by Virendra K Sharma et al. in 2016.[9]

In our study, total DPN was 59% (118 patients). Out of the 118 patients, 45.8% were females and 54.2% were males. The incidence of peripheral neuropathy was almost the same in both gender according to JiNa et al. in 2012.[18] Similar results were seen in a study by Katulanda P et al.[15]

We found that DPN was more in all group of diabetes, but more increased in the group of 5–10 years duration of diabetes (64.3%, 72/112) and >20 years duration of diabetes (62.5%, 10/16).

Kumar HK et al., in a study done at Lucknow in 2012, concluded that diabetic peripheral neuropathy was more in individuals who had a longer course of disease.[19]

Won JC et al. in their study performed in Korea and published in 2012 also found duration as a risk factor for diabetic peripheral neuropathy.[17]

The JI Na et al.[18] study conducted in China 2011 showed that prevalence of DPN increases with increase in duration of diabetes mellitus.

The findings of all the studies matched with that of the current study.

DPN was seen to be considerably higher in patients with uncontrolled DM (HbA1c >7%) than that with controlled DM. 27 out of 61 (44.3%) patients in controlled group had DPN, 91 out of 139 (65.46%) patients in uncontrolled diabetes group had DPN with AP value of 0.005.

Kumar HK et al. in their study done in Lucknow in 2012 concluded that there is increased risk of developing microvascular complications, including DPN in patients with a higher value of Glycosylated Haemoglobin (HbA1c).86 In a study done by Salwa SIA et al.[14] in Malaysia79 in 2012 he identified HbA1c to be a modifiable risk factor for DPN.

Won JC et al. from Korea, in their study published in 2012, showed similar findings. They found higher levels of HbA1c in patients suffering from DPN. They also noticed that the proportion of patients with diabetic peripheral neuropathy increased with the HbA1c level.[87]

The Ji Na et al.[18] study conducted in China, 2011 showed that 34.8% diabetic patients with neuropathy had HbA1c >9%, whereas 39.2% cases with neuropathy had HbA1c values from 7% to 9%. Only 26% of cases in their study had HbA1c values less than 7%. This study made similar groups, but their results show much less prevalence than what was obtained in our study.

Out of 45% (90 patients) with positive family history for diabetes, 46 patients (51.1%) had neuropathy and 44 (48.9%) had no neuropathy. Out of 55% (110 Patients) with no family history of diabetes, 72 patients (65.45%) had neuropathy and 38 had no neuropathy (34.5).

Our study showed there was statistically significant difference in the occurrence of DPN with respect to family history of diabetes, with P = 0.04.

In this study, correlation between the prevalence of diabetic retinopathy in individuals with and without diabetic peripheral neuropathy was studied to establish a relation between the two.

62.5% of the cases had one or both the above microvascular complications. DR alone was present in 3.5%, and 34.5% of the cases had only neuropathy.

Prevalence of DR in the presence of DPN was 41.5% (49/118), and in the absence of DPN was 8.5% (7/82, P < 0.001). This clearly shows that the prevalence of diabetic retinopathy in cases with diabetic peripheral neuropathy was 4.88 times than in cases without diabetic peripheral neuropathy. There exists statistically significant difference between the two groups.

Higher grades of DR were present in patients with DPN than patients without diabetic peripheral neuropathy.

86% of mild NPDR was seen in neuropathic patients and 14% was seen in patients without diabetic neuropathy. 86% of moderate NPDR was seen in diabetic neuropathic patients and 14% was seen in patients without diabetic neuropathy. 80% of severe NPDR was seen in diabetic neuropathy patients with 20% patients without diabetic neuropathy. Almost all PDR patients were seen in patients with diabetic peripheral neuropathy (100%). The above difference were statistically significant and the P = 0.001.

Our study differed from the following studies in that they found that diabetic retinopathy was relatively more in patients with diabetic peripheral neuropathy.

Hari KVS Kumar et al. in their study[19] on Indian population concluded that neuropathy was seen more in patients with coexisting retinopathy than in those without retinopathy.

Salwa SIA et al.[14] in their study at Malaysia in 2012 showed retinopathy as one of the most important risk factors for diabetic peripheral neuropathy. They also observed that diabetic retinopathy was 2.85 times more likely to develop in patients having peripheral neuropathy. The finding was almost equal to our study in which the relation was of 2.75 times.

Won JC et al. from Korea in their study published in 2012 showed that the prevalence of diabetic retinopathy in the person suffering from diabetic peripheral neuropathy was 1.78 times more than those without diabetic peripheral neuropathy.[17]

Katulanda P et al.[15] in their study on the prevalence of DPN in 2012 found that their subjects of diabetic peripheral neuropathy had a significant relation with DR. They found that DR was 2.7 times more common in patients having DPN than in those who did not have DPN.

CONCLUSION

We found a higher prevalence of retinopathy in patients with neuropathy, and thus, a lookout for peripheral neuropathy should be kept in diabetics presenting to us with retinopathy.

Financial support and sponsorship

Nil.

Conflicts of interest

There are no conflicts of interest.