Oral Galactose as a Substrate for Post-Exercise Skeletal Muscle Glycogen Repletion in Individuals With Type 1 Diabetes

This Ph.D. project investigates whether orally ingested galactose can be taken up by skeletal muscle and the heart in response to exercise or hyperinsulinemia, and whether it may serve as a viable nutritional strategy for individuals with type 1 diabetes (T1D). Although exercise provides significant health benefits for people with T1D, it is often associated with substantial glucose fluctuations and an increased risk of hypoglycemia. Conventional carbohydrate strategies based on glucose may further exacerbate glycemic instability due to the rapid increase in blood glucose levels. In contrast, galactose is metabolized more slowly and may therefore provide a more stable energy source during and after exercise. Previous research has demonstrated that intravenously administered galactose is taken up by human skeletal muscle, with uptake increasing during exercise, suggesting a mechanism that may be at least partly insulin-independent. Building on these findings, this project aims to determine whether similar uptake occurs when galactose is ingested orally. This study uses a randomized controlled design and applies non-invasive 18F-FDGal PET imaging to quantify galactose uptake in skeletal muscle and cardiac tissue. The findings may contribute to improving dietary recommendations for individuals with T1D, particularly in relation to maintaining stable blood glucose levels during and after physical activity.

Inclusion Criteria: * Healthy or T1D * BMI 18,5-30 kg/m2 * Singed informed consent Exclusion Criteria: * Clinically significant heart, lung, kidney, liver, endocrine, or malignant disease based on information collected during the initial screening visit as well as blood tests * Lack of awareness of hypoglycemia episodes * Blood donation within the last 3 months * Smoking * Alcohol or substance abuse * Participation in other studies involving ionizing radiation within the last 6 months * Claustrophobia * Inability to train one leg for one hour