The amount of oral carbohydrate (CHO) needed to prevent hypoglycemia during prolonged fasted exercise in CSII is unclear. We assessed CHO intake needs during 3 different basal rate strategies during prolonged fasted exercise in active patients with T1D.

Individuals with T1D on CSII (n=15) completed three 120-min treadmill exercise (∼45% of VO2peak) visits in a randomized crossover design. Strategies included: A) no basal rate reduction (BRR) and a dextrose intake of 0.3 g/kg/hr when BG was <10mmol/L (CHO only); B) a 50% BRR set 90 min pre-exercise, with dextrose as needed to treat hypoglycemia (50% BRR); and C) a 50% BRR set at exercise start plus dextrose intake of 0.3 g/kg/hr when BG was <10 mmol/L (Combo).

Glycemia was higher in C compared to A or B by 105 min of exercise (P < 0.05). The drop in blood glucose during exercise was greater in A (-2.7 ± 3.4 mmol/L) than in B (-1.9 ± 2.5 mmol/L) or C (0.3 ± 2.6 mmol/L). Total CHO intake was 38.0 ± 18.8 g, 0.8 ± 3.1 g, and 29.5 ± 16.2 g, for A, B and C, respectively. Compared to A, B had lower RER (0.83 ± 0.04 vs. 0.79 ± 0.04), higher ketones (0.1 ± 0.1 vs. 0.4 ± 0.3 mmol/L), greater net loss of calories (709.2 ± 217.4 vs. 859.7 ± 239.6 kcal) and greater fat oxidation rate (0.39 ± 0.1 vs. 0.51 ± 0.2 g/min) (all P < 0.05).

A BRR, set 90 min prior to exercise is associated with good glycemic control and an increased rate of lipid oxidation compared to CHO feeding alone or combined BRR and CHO feeding approach at exercise onset.


S.M. McGaugh: None. R. Pooni: None. D. Zaharieva: Speaker’s Bureau; Self; Ascensia Diabetes Care, Insulet Corporation, Medtronic. N.C. D’Souza: None. T. Vienneau: Employee; Self; Insulet Corporation. Stock/Shareholder; Self; Insulet Corporation. T.T. Ly: Employee; Self; Insulet Corporation. M. Riddell: Advisory Panel; Self; Zucara Therapeutics Inc. Consultant; Self; Lilly Diabetes. Research Support; Self; Dexcom, Inc., Insulet Corporation. Speaker’s Bureau; Self; Medtronic, Novo Nordisk A/S.


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