Impact of pre- and post-exercise strategies on hypoglycemic risk for two modalities of aerobic exercise among adults and adolescents living with type 1 diabetes using continuous subcutaneous insulin infusion: A randomized controlled trial

Abstract

Objective: We investigated strategies to mitigate hypoglycemic risk during and after different aerobic exercises in people with type 1 diabetes (pwT1D) using continuous subcutaneous insulin infusion.

Research design and methods: Thirty-seven pwT1D (21 adults, 16 adolescents; HbA1c = 7.5 ± 1.0 %) participated in two post-absorptive (4-h post-meal) exercise sessions (60-min continuous moderate intensity [CONT] vs. intermittent [INT]). Pre-exercise basal rate reduction (BRR) was either 40 % or 80 %, 90 min before exercise. Post-exercise, participants undertook either a 20 % BRR for 10 h with 20 % reduced dinner bolus (INS) or a 45 g post-exercise carbohydrate (CHO) snack with a 50 % insulin bolus, and a 30 g bedtime CHO snack without bolus (snack).

Results: While a similar number of hypoglycemic events (31 vs. 28) were observed between exercise modalities, CONT led to a greater decrease in blood glucose during exercise compared to INT (-3.1 ± 2.3, CONT vs. -2.7 ± 2.2 mmol/l, INT, P = 0.005). Changes in blood glucose during exercise (-3.0 ± 2.4, 40 %BRR vs. -2.8 ± 2.1 mmol/l, 80 %BRR, P = 0.076) and the number of hypoglycemic events (35 vs. 24) were similar between 40 % and 80 %BRR. Time in hyperglycemia was lower with INS compared to snack in the first 30 min after exercise, but no differences were observed for late recovery period or nighttime.

Conclusion: Compared to INT, CONT led to greater blood glucose decline without increasing hypoglycemia risk. A larger pre-exercise BRR did not further reduce hypoglycemia risk during exercise. Post-exercise INS and snack strategies led to comparable glucose profiles in pwT1D.

Keywords: Exercise modality; Hypoglycemia; Insulin basal rate reduction; Mitigation strategies; Physical activity.