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

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.