A single load of fructose attenuates the risk of exercise-induced hypoglycaemia in adults with type 1 diabetes on ultra-long-acting basal insulin - a randomised, open-label, crossover proof-of-principle study

<b>Objective</b> <p>While the adjustment of insulin is an established strategy to reduce the risk of exercise-associated hypoglycaemia for individuals with type 1 diabetes, it is not easily feasible for those treated with ultra-long acting basal insulin. The present study determined whether pre-exercise intake of fructose attenuates the risk of exercise-induced hypoglycaemia in individuals with type 1 diabetes using insulin degludec.</p> <p><b>Research design and method</b></p> <p>Fourteen male adults with type 1 diabetes completed two 60min aerobic cycling sessions with or without prior intake (30min) of 20g of fructose, in a randomised two-period crossover design. Exercise was performed in the morning in a fasted state without prior insulin reduction, and after 48h of standardised diet. The primary outcome was time to hypoglycaemia (plasma glucose ≤3.9mmol/L) during exercise.</p> <p><b>Results</b></p> <p>Intake of fructose resulted in one hypoglycaemic event at 60min compared to six hypoglycaemic events at 27.5±9.4min of exercise in the control condition, translating into a risk reduction of 87.8% (hazard ratio 0.12 [95% CI 0.02; 0.66]; p=0.015). Mean plasma glucose during exercise was 7.3±1.4mmol/L with fructose and 5.5±1.1mmol/L during control (p<0.001). Lactate levels were higher at rest in the 30min following fructose intake (p<0.001) but were not significantly different from control during exercise (p=0.32). Substrate oxidation during exercise did not significantly differ between the conditions (p=0.73 for carbohydrate and p=0.48 for fat oxidation). Fructose was well tolerated.</p> <p><b>Conclusions</b></p> <p>Pre-exercise intake of fructose is an easily feasible, effective and well-tolerated strategy to alleviate the risk of exercise-induced hypoglycaemia whilst avoiding hyperglycaemia in individuals with type 1 diabetes on ultra-long acting insulin. </p>