| Literature DB >> 25717279 |
Dessi P Zaharieva1, Michael C Riddell1.
Abstract
Entities:
Year: 2015 PMID: 25717279 PMCID: PMC4334080 DOI: 10.2337/diaspect.28.1.55
Source DB: PubMed Journal: Diabetes Spectr ISSN: 1040-9165
Carbohydrate Intake Strategies Based on Pre-Exercise Blood Glucose Level
| Pre-Exercise Blood Glucose Concentration | Action |
| <90 mg/dL | Ingest 15–30 g of fast-acting carbohydrates before the onset of exercise, depending on the size of the individual. Follow with extra carbs throughout exercise. |
| 90–149 mg/dL | Start consuming extra carbs at the onset of exercise (∼0.5–1.0 g/kg body mass/hour of exercise), depending on the energy expenditure and the amount of circulating insulin at the time of exercise. |
| 150–249 mg/dL | Initiate exercise and delay consumption of extra carbs until blood glucose levels drop to <150 mg/dL. |
| 250–349 mg/dL | Test for ketones: do not perform any exercise if moderate to large amounts of
ketones are present ( |
| ≥350 mg/dL | Test for ketones: do not perform any exercise if moderate to large amounts of
ketones are present ( |
Blood glucose concentrations should always be checked before exercise, and if glucose is dramatically elevated (≥350 mg/dL), the urine or blood should also be tested for ketones. The target range for blood glucose before exercise is 90–250 mg/dL. Carbohydrate intake should depend on the glucose concentration at the start of exercise. Regardless of their initial blood glucose concentration, patients should continue to monitor blood glucose regularly during exercise (every 30–45 minutes) using an accurate glucose meter and to adjust insulin and carbohydrate intake accordingly. In general, adjusting insulin doses before exercise will reduce the need for increased carbohydrate intake. Adapted from Refs. 26 and 27.
Carbohydrate Intake Strategies Based on CGM Readings
| Sensor Glucose (mg/dL) | Trend Arrows | Carbohydrate Intake (g) |
| 109–124 | ↓ or ↓↓ | 8 (2 glucose tablets) |
| 90–108 | ↓ | 16 (4 glucose tablets) |
| ↓↓ | 20 (5 glucose tablets) | |
| <90 | No arrow | 16 (4 glucose tablets) |
| ↓ or ↓↓ | 20 (5 glucose tablets) |
This carbohydrate protocol can be used if CGM-measured glucose is <125 mg/dL and dropping. Because this algorithm was tested in adolescents with type 1 diabetes (15), adults may require more carbohydrate. For safety, people with diabetes should stop exercising if hypoglycemia develops (capillary blood glucose ≤65 mg/dL) and treat with 15–20 g of rapid-acting carbohydrates (28). CGM is not a substitute for capillary glucose monitoring. It should be noted that the CGM trend arrows differ slightly in appearance and display messaging, depending on the type of CGM system used. This table represents the trending arrows for the Medtronic CGM system that was used in this study. The Medtronic system shows a single downward arrow to indicate a rate of decrease in the glucose level of 1–2 mg/dL/minute; two downward arrows indicates that glucose levels are falling by ≥2 mg/dL/minute. The Dexcom CGM system displays a single downward-pointing diagonal arrow to indicate a drop in glucose of 1–2 mg/dL/minute, a single vertical downward-pointing arrow to indicate a drop rate of 2–3 mg/dL/minute, and two downward-pointing vertical arrows to indicate a drop rate >3 mg/dL/minute.
Percentage Reductions in Bolus Insulin for 30 or 60 Minutes of Aerobic Exercise Performed Within 2–3 Hours After a Meal (6)
| Bolus Dose Reduction for 30 Minutes of Exercise (%) | Bolus Dose Reduction for 60 Minutes of Exercise (%) | |
| Mild (e.g., walking, gardening, or shopping) | 25 | 50 |
| Moderate (e.g., brisk walking, jogging, light cycling, or skating) | 50 | 75 |
| Intense (e.g., intense cycling, running, dancing, or individual or team sports) | 75 | — |
The subjects in this study were all on multiple daily injection insulin regimens using ultralente insulin as their basal insulin and lispro as their mealtime insulin. Using different basal and bolus insulins or using an insulin pump instead of taking multiple daily injections may influence the percentage of reduction in bolus insulin needed for aerobic exercise.
Percentage Reductions in Basal Insulin for 60 Minutes of Aerobic Exercise Performed by People Who Use an Insulin Pump and Exercise After a Meal
| Aerobic Exercise Intensity | Basal Rate Reduction for 60 Minutes of Exercise (%) |
| Mild | 30 |
| Moderate | 50 |
| Intense | 90–100 |
Basal rate reductions should be made 60–90 minutes before the onset of exercise and should last until the activity is completed. Prolonged disconnection of the pump or reductions in the basal rate to 0 may result in hyperglycemia. Individuals should test their glucose levels frequently and resume basal insulin delivery or provide bolus delivery if glucose levels are rising toward the hyperglycemic range.