743-P: New Insulin Algorithm Reduces Carbohydrate (CHO) Requirements during Prolonged Outdoor Exercise

Individuals with T1D are generally advised to reduce basal rates and increase CHO intake during aerobic exercise. We assessed the effects of a different insulin regimen guided by rtCGM data on CHO intake and glucose levels in 17 T1D adults treated with insulin pumps (11 male, 42±8.8 years, 24±10 years DM duration, 6.6±0.8% A1C) vs. traditional insulin adjustment guidance during 2 consecutive days of extended biking activities (30 miles [49 km]). On day 1 (D1), subjects reduced their basal rate by 50% and consumed CHO as guided by their rtCGM (Dexcom G6) data to maintain target range (70-180 mg/dL). Basal insulin infusion was stopped 1 hour at the start of the day 2 activity (D2) then resumed at a minimal rate (0.23±0,1U/hour) during biking. All CHO from 1 hour before, during and 10 min after the activity was recorded. Times within/below target range, glycemic variability (GV) and mean glucose were calculated from rtCGM data. CHO intake was notably lower during D2 vs. D1 (36±32 vs. 40±27 g, p=NS), with slightly more time in range and