5 - The Association of Exercise Blood Glucose on Postexercise Hypoglycemia in Type 1 Diabetes

Abstract

Guidelines suggest that people with type 1 diabetes (T1D) start exercise with moderately high blood glucose (8-10 mmol/L) (BG) to reduce the risk of hypoglycemia; however, those fearing hypoglycemia often start higher. This study aimed to determine the impact of afternoon aerobic exercise with a higher BG on postexercise glycemia, as measured by continuous glucose monitoring (CGM). Eleven active T1D participants (8F/3M, 30[8] years, A1C 7.7[0.8]%, VO2peak 38.4[7.7] ml/kg/min) completed 2 exercise sessions in random order: 1) with BG between 8.0-10.0 mmol/L (MOD) and 2) with BG between 12.0-14.0 mmol/L (HI). Participants were asked to keep meal timing/composition and insulin doses consistent between sessions. Participants cycled 45 minutes at 60%VO2peak. Exercise intensity (respiratory exchange ratio, heart rate) was identical between sessions (p>0.05). CGM data (mean[SD]) were assessed between 6:00 pm - 12:00 am (6 hr) and 12:00 am - 6:00 am (nocturnal) after exercise. ANOVA revealed a main effect of condition for mean CGM glucose (MOD vs HI, 6 hr: 8.8[1.0] vs 10.5[2.6] mmol/L; nocturnal: 8.6[1.4] vs 9.8[2.8] mmol/L; p=0.03), percent time in range (MOD vs HI, 6 hr: 76[16] vs 48[28]%; nocturnal: 72[33] vs 58[33]%, p<0.01) and percent time in hyperglycemia (MOD vs HI, 6hr: 24[16]% vs 49[29]%; nocturnal: 27[31] vs 42[33]%, p<0.01). There were no differences with respect to hypoglycemia. Overall, higher exercise BG was not associated with any protection against hypoglycemia, but instead increased hyperglycemia and decreased time in range.