Galactose - the Ideal Carbohydrate Supplement for Exercise in Type 1 Diabetes

In this study, 14 subjects with type 1 diabetes are studied in a randomized crossover study in which the subjects cycle at a fixed intensity at 60% of their maximum oxygen capacity (VO2 max) for 1 hour. Thirty minutes before each cycling test, participants consume a 200 ml beverage, consisting of either: 1) dextrose (20 g), 2) galactose (20 g), 3) lactose (20 g) or 4) water (sweetened). If blood sugar drops below 3.9 mmol/l, glucose infusion is given and blood sugar is kept just above 5 mmol/L. The trial days take place at least 4 days apart.

Inclusion Criteria: * type 1 diabetes for at least 2 years * age between 18 and 65 years * HbA1c less than 70 mmol/mol * Physically active (at least 150 minutes of moderate-to-vigorous intensity activity weekly) * Insulin pen and pump treatment * Men and women are eligible, but women will have to perform study days in the mid-cycle phase of the menstrual cycle. Exclusion Criteria: * \- Diabetic nephropathy, neuropathy, and proliferative retinopathy * Hypoglycemia unawareness * Lactose intolerance * Heart disease and other conditions which may be negatively affected by the VO2 max test and 1-hour cycling on study days