Background:
People with type 1 diabetes practicing a low-carbohydrate diet can increase the fat and/or protein content of the diet to cover their energy needs. In relation to physical activity, ingestion of protein is preferable for muscle protein synthesis and enhances structural changes in non-muscle tissues such as tendons and bones. Furthermore, addition of ≥ 28 g of protein to a meal is likely to result in significant and sustained postprandial hyperglycemia commencing in the late postprandial period (2-3 h) and continuing beyond 5 h in people with type 1 diabetes. The protein-induced change in the postprandial glucose response could be beneficial in relation to prevention of exercise-induced hypoglycemia. Hypoglycemia is a common fear in people with type 1 diabetes and makes many abstain from exercising.
This study investigates the effect of a low-carbohydrate-high-protein pre-exercise meal on preventing exercise-induced hypoglycemia in people with type 1 diabetes. The hypothesis is that intake of a low-carbohydrate-high-protein meal can reduce the duration and depth of hypoglycemia during and after exercise in people with type 1 diabetes compared with an isocaloric high-carbohydrate-low-protein meal with identical fat content.
This study will contribute with new knowledge about importance of meal composition on preventing exercise-induced hypoglycemia. The study may add new aspects to current guidelines for glucose management during exercise in people with type 1 diabetes. If the strategy has a positive effect on preventing exercise-induced hypoglycemia it will be useful to all people with type 1 diabetes irrespective of diet strategy.
Study design:
The study is a randomized, two-arm crossover trial including one screening visit, two study days and a short visit after each study day, where the participants must meet to upload research data. The study will include adults with type 1 diabetes on insulin pump therapy using flash glucose monitoring (FGM) or continuous glucose monitoring (CGM). 15 participants have to complete the study. The study days are identical except for the content of the pre-exercise meal (low-carbohydrate-high-protein meal versus high-carbohydrate-low-protein meal) and the size of the meal bolus. Meals are isocaloric. The participants will complete two study days in random order with a 10-14 days washout period between. 48 hours prior to each study day blood glucose will be monitored by CGM and activity level will be monitored by an activity monitor wristband.
Each study day is divided into an in-clinic period, which takes place at Steno Diabetes Center Copenhagen (SDCC), and a home period, which takes place in the participants own homes.
The participants will arrive at the research facility in the morning following an overnight fast. A pre-exercise meal with either low-carbohydrate-high-protein content or high-carbohydrate-low-protein content will be served. To estimate the gastric emptying 1g paracetamol will be added to the meal. After ingesting the meal and 90 min of resting the participants must perform 45 min of exercise on an ergometer cycle equaling to 60 % of their peak oxygen consumption or until hypoglycemia (plasma glucose \< 3.9) or unbearable symptoms of hypoglycemia. Throughout the in-clinic study day the participants must use their insulin pumps. The basal insulin rate and meal-bolus will be adjusted according to international guidelines. Blood samples for analysis of glucose, insulin, glucagon, cortisol, adrenalin, noradrenalin, growth hormone, ketones, lactate, free fatty acids, GLP1, GIP and inflammatory markers will be collected. Indirect calorimetry will be performed before, during and after exercise to measure energy expenditure, respiratory exchange ratio and carbohydrate and fat oxidation rates. The Borg Scale will be used to assess perceived exertion during the exercise and a visual analog scale will be used to assess the feeling of satiety during the study day.
Leaving SDCC the home period begins. Throughout the home period the blood glucose and activity level will be monitored by the CGM and the activity monitor until the next morning, where the study day ends. From the research facility the participants will be provided a standard evening meal and a bedtime snack. The participants will also be provided dextrose tablets, which they must ingest in case of hypoglycemia. Within one week after both study days, the participants must meet at the clinic to upload research data.
