Exercise Volume and Beta-cell Function in T2D The DOSE-EX Randomized Trial

A 4‐armed, 16‐week, parallel‐group, assessor‐blinded, randomized, clinical trial. Participants will be randomly allocated (1:1:1:1), stratified by sex Interventions: The lifestyle interventions will consist of two main components; 1) increased physical activity and structured exercise and/or 2) a dietary intervention aiming at a weight loss. Whereas there will be no differences in the dietary intervention between the lifestyle groups, the volume of physical activity and structured exercise will vary according to the frequencies of the structured exercise sessions. The study groups are prescribed: 1. Control group (CON): No intervention 2. Dietary control (DCON): Dietary intervention (see below) 3. Moderate Exercise Dose (MED): Two aerobic training sessions per week of 45‐60 min duration and one session per week with combined aerobic (30‐35 min) and resistance (30 min) training and a dietary intervention (described below) 4. High Exercise Dose (HED): Four aerobic training sessions per week of 45‐60 min duration and two sessions per week with combined aerobic (30‐35 min) and resistance (30 min) training and a dietary intervention (described below) Detailed description of the intervention components. Exercise: The training protocol will be adapted based on a previous study where the T2D participants were prescribed 6 weekly sessions of aerobic training alone or combined aerobic and resistance training (averaging 360‐420 min of exercise per week). As previous analyses suggest that there may be an inverse dose‐response relationship between reductions in HbA1c and aerobic exercise volume, this parameter will be used to adapt the training protocol. As the effect of exercise on HbA1c is closer related to the number of training sessions rather than intensity15, we will reduce the number of sessions by 50%, to three sessions/week in the moderate exercise dose group and maintain the original session frequency in the high dose exercise group (six sessions/week).Training will be supervised and monitored to ensure intensity and compliance. Dietary intervention and intended weight loss (DCON, MED and HED: The dietary intervention will be based on the recommendations from the American Diabetes Association (ADA) with increased focus on macronutrient quality. The macronutrient distributions are in line with the current guidelines from the national Diabetes Association and Canadian guidelines, where individualization in macronutrient distribution should lie within the range of 45‐60 energy% carbohydrate, 15‐20 energy% protein and 20‐35 energy% fat. Thus, the dietary intervention emphasis will be on low glycemic index and low glycemic load in shape of non‐processed foods and will aim at reducing saturated fat intake <7 energy%.