In-exercise Carbohydrate Consumption Stabilises Glycaemia, Lowers Carbohydrate Oxidation And Glucoregulatory Responses In Type 1 Diabetes

PURPOSE: To compare the effects of isocaloric carbohydrate intake before or during exercise on glycaemic, fuel oxidation and glucoregulatory hormone responses in type 1 diabetes (T1D) adults using an automated insulin delivery system. METHODS: T1D participants (n = 8, 5 female, age 47 ± 16 years, BMI 27.5 ± 3.8 kg/m2, diabetes duration 23 ± 11 years, HbA1c 8.3 ± 0.9 (67.5 ± 9.5) % (mmol/mol)) consumed a carbohydrate drink (10% concentration) as either, single bolus (0.75 g CHO/kg) 90 minutes before 45-min cycle at 60% VO2peak (PEC) or 3 x 0.25 g CHO/kg during exercise (DEC). Plasma glucose, gut peptides, glucoregulatory hormones and fuel oxidation were determined. Data were treated via 2-way repeated measures ANOVA with p ≤ 0.05 accepted, where appropriate. RESULTS: PG during exercise increased in DEC by +0.04 ± 0.03 mmol/L/min and decreased in PEC by -0.07 ± 0.03 mmol/L/min (p < 0.001 between conditions). Carbohydrate oxidation rate and percent of total energy was lower (DEC 0.63 ± 0.19 vs. PEC 0.80 ± 0.21 g/min, P = 0.009; DEC 53.4 ± 7.5 % vs. PEC 64.1 ± 13.3, P = 0.06), and lipid oxidation rate greater (P = 0.014) in DEC than PEC. Serum GLP-1, GIP, glucagon, and total insulin concentrations during exercise were lower in DEC compared to PEC (see Figure 1). CONCLUSIONS: In people with type 1 diabetes using automated insulin delivery systems, carbohydrate consumption during aerobic exercise stabilised plasma glucose, lowered carbohydrate oxidation and resulted in lower changes in gut peptides, pancreatic glucagon and circulating insulin when compared to carbohydrate intake before exercise. These data help support better exercise nutrition recommendations for automated insulin delivery users. Figure 1: Resting and exercise serum (A) GLP-1, (B) GIP, (C) Glucagon and (D) plasma insulin concentrations. Data (mean ± SD) are presented for n = 8. *indicates significant difference between conditions, hollow symbols represent significant differences from REST within trial.