Pre‐Exercise Galactose or Lactose Reduces Glycaemic Excursions During Exercise in Adults With Type 1 Diabetes: A Randomised, Double‐Blind, Crossover Trial

Aims To test whether pre‐exercise galactose and lactose reduce glycaemic excursions during exercise compared with dextrose while maintaining protection against hypoglycaemia compared with placebo in adults with Type 1 diabetes Methods In a randomised, double‐blind, 4‐condition crossover trial, 14 adults with Type 1 diabetes completed four 60‐min cycling sessions. Thirty minutes before exercise, participants consumed 20 g of dextrose, lactose, galactose, or placebo. The primary outcome was time to hypoglycaemia. Secondary outcomes included time in, below, and above range and glucose excursions. Results Seven hypoglycaemic events occurred (none after dextrose, two after lactose, one after galactose, and four after placebo; p = 0.42), with no difference in time to hypoglycaemia. Time in range was lower for dextrose (48% [95% CI 40–57]) compared with lactose (70% [95% CI 62–78]), galactose (71% [95% CI 63–79]), and placebo (86% [95% CI 80–91]) (all p ≤ 0.01). Time below range was lower for dextrose (0% [95% CI 0–3]), lactose (1% [95% CI 0–5]), and galactose (1% [95% CI 0–5]) compared with placebo (8% [95% CI 4–14]) (all p < 0.05). Time above range was higher for DEX (52% [95% CI 44–60]), LAC (29% [95% CI 21–37]), and GAL (28% [95% CI 21–36]) compared with PLA (7% [95% CI 3–12], all p < 0.01). Conclusions Pre‐exercise galactose and lactose provide more stable glycaemic responses than dextrose and reduce time below range compared with placebo. These findings support their use as effective pre‐exercise nutritional strategies in individuals with Type 1 diabetes. Trial Registration: ClinicalTrials.gov identifier: NCT05557227.