Individual glucose responses to prolonged moderate intensity aerobic exercise in adolescents with type 1 diabetes: The higher they start, the harder they fall

Abstract

Objective To evaluate the pattern of change in blood glucose concentrations and hypoglycemia risk in response to prolonged aerobic exercise in adolescents with type 1 diabetes (T1D) that had a wide range in pre‐exercise blood glucose concentrations. Methods Individual blood glucose responses to prolonged (~60 minutes) moderate‐intensity exercise were profiled in 120 youth with T1D. Results The mean pre‐exercise blood glucose concentration was 178 ± 66 mg/dL, ranging from 69 to 396 mg/dL, while the mean change in glucose during exercise was −76 ± 55 mg/dL (mean ± SD), ranging from +83 to −257 mg/dL. Only 4 of 120 youth (3%) had stable glucose levels during exercise (ie, ± ≤10 mg/dL), while 4 (3%) had a rise in glucose >10 mg/dL, and the remaining (93%) had a clinically significant drop (ie, >10 mg/dL). A total of 53 youth (44%) developed hypoglycemia (≤70 mg/dL) during exercise. The change in glucose was negatively correlated with the pre‐exercise glucose concentration (R2 = 0.44, P < 0.001), and tended to be greater in those on multiple daily insulin injections (MDI) vs continuous subcutaneous insulin infusion (CSII) (−98 ± 15 vs −65 ± 7 mg/dL, P = 0.05). No other collected variables appeared to predict the change in glucose including age, weight, height, body mass index, disease duration, daily insulin dose, HbA1c, or sex. Conclusion Youth with T1D have variable glycemic responses to prolonged aerobic exercise, but this variability is partially explained by their pre‐exercise blood glucose levels. When no implementation strategies are in place to limit the drop in glycemia, the incidence of exercise‐associated hypoglycemia is ~44% and having a high pre‐exercise blood glucose concentration is only marginally protective.

Pre-Exercise Blood Glucose Levels Determine the Amount of Orally Administered Carbohydrates during Physical Exercise in Individuals with Type 1 Diabetes—A Randomized Cross-Over Trial

“…Additionally, even though our participants were trained on carbohydrate counting, a few pre-exercise bolus insulin under-dosages were observed, contributing to a time spent in hyperglycemia of 17.2% of total time (Figure 2). However, such elevated pre-exercise blood glucose levels are often seen in individuals with type 1 diabetes [16] hence indicating a transferability of our study results to the real-life condition of our study.…”

“…Initially, research showed a linear blood glucose decrease during endurance exercise depending on the mean exercise intensity [11]. Intriguingly, it was recently shown that the decline in blood glucose levels during physical exercise is associated with pre-exercise blood glucose levels in children with type 1 diabetes (‘the higher the start, the harder they fall’) [16]. The undesired side-effect of physical exercise was also illustrated within this study: if the drop in the blood glucose concentration was not treated with orally administered carbohydrates, the incidence of exercise-induced hypoglycemia was ~44%.…”

Glucose management for exercise using continuous glucose monitoring (CGM) and intermittently scanned CGM (isCGM) systems in type 1 diabetes: position statement of the European Association for the Study of Diabetes (EASD) and of the International Society for Pediatric and Adolescent Diabetes (ISPAD) endorsed by JDRF and supported by the American Diabetes Association (ADA)

“…Preparation in advance to exercise For the immediate preexercise phase, the target sensor glucose range should be between 7.0 mmol/l and 10.0 mmol/l (126 mg/dl and 180 mg/ dl), or between 8.0 mmol/l and 11.0 mmol/l (145 mg/dl and 198 mg/dl) for children and adolescents moderately exercising and/or with a moderate risk of hypoglycaemia, and 9.0 mmol/l and 12.0 mmol/l (162 mg/dl and 216 mg/dl) for children and adolescents minimally exercising and/or with a high risk of hypoglycaemia [40] (D), [93] (D). These glucose targets can be achieved by mealtime insulin dose reduction ranging from 25% to 75% (Table 4) [38] (D), [39] (D), [40] (D).…”

Accuracy of the Dexcom G6 Glucose Sensor during Aerobic, Resistance, and Interval Exercise in Adults with Type 1 Diabetes

“…Among the many challenges people with type 1 diabetes face when exercising, fear of hypoglycemia has been identified as the strongest barrier [ 5 ]. Moderate intensity aerobic exercise, for example, is known to cause sharp drops in glucose levels [ 6 , 7 ]. Conversely, high intensity exercises such as resistance training or high intensity interval training (HIIT) can lead to hyperglycemia [ 8 , 9 ].…”