Christoph Stettler

Aim To evaluate whether caffeine combined with a moderate amount of glucose reduces the risk for exercise‐related hypoglycaemia compared with glucose alone or control in adult people with type 1 diabetes using ultra‐long‐acting insulin degludec. Materials and Methods Sixteen participants conducted three aerobic exercise sessions (maximum 75 min) in a randomized, double‐blind, cross‐over design. Thirty minutes before exercise, participants ingested a drink containing either 250 mg of caffeine + 10 g of glucose + aspartame (CAF), 10 g of glucose + aspartame (GLU), or aspartame alone (ASP). The primary outcome was time to hypoglycaemia. Results There was a significant effect of the condition on time to hypoglycaemia (χ 2 = 7.674, p = .0216). Pairwise comparisons revealed an 85.7% risk reduction of hypoglycaemia for CAF compared with ASP ( p = .044). No difference was observed between GLU and ASP ( p = .104) or between CAF and GLU ( p = .77). While CAF increased glucose levels during exercise compared with GLU and ASP (8.3 ± 1.9 mmol/L vs. 7.7 ± 2.2 mmol/L vs. 5.8 ± 1.4 mmol/L; p < .001), peak plasma glucose levels during exercise did not differ between CAF and GLU (9.3 ± 1.4 mmol/L and 9.1 ± 1.6 mmol/L, p = .80), but were higher than in ASP (6.6 ± 1.1 mmol/L; p < .001). The difference in glucose levels between CAF and GLU was largest during the last 15 min of exercise ( p = .002). Compared with GLU, CAF lowered perceived exertion ( p = .023). Conclusions Pre‐exercise caffeine ingestion combined with a low dose of glucose reduced exercise‐related hypoglycaemia compared with control while avoiding hyperglycaemia.