Improved end-stage high intensity performance but similar glycaemic responses after waxy barley starch ingestion compared to dextrose in type 1 diabetes.

Introduction - Pre-exercise carbohydrate (CHO) ingestion is an effective strategy for reducing the occurrence of hypoglycaemia during or after exercise in individuals with type 1 diabetes (T1DM). The metabolic effects of ingestion of different CHOs for glycaemic or performance gains have been under-researched. This study compared metabolic responses and fuel use during sub-maximal and high-intensity performance running following preexercise ingestion of waxy barley starch (WBS) or dextrose (DEX) in T1DM. Methods - Seven participants attended the laboratory on two separate occasions following preliminary testing. On each visit participants consumed either 0.6 g.kg-1 body mass of DEX or WBS 2-h before a 26-min discontinuous incremental treadmill protocol (4-min running: 1.5-min rest) finishing at 80±4% O2peak followed by a 10-min performance run on a nonmotorised treadmill. Capillary blood samples were taken at rest, during and following exercise and analysed for glucose (BG) and acid-base variables. Data (mean±SEM) were analysed using repeated measures ANOVA (P0.05). In the final quartile of the performance run, a greater distance was completed under WBS (WBS 323±21 vs. DEX 301±20 m, P=0.02). Conclusions - Consumption of WBS demonstrated similar hyperglycaemic responses to dextrose ingestion but a greater rate of CHO use at rest. Interestingly, T1DM individuals displayed an improved performance at the latter stages of a high-intensity run test.