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:

• Control group (CON): No intervention
• Dietary control (DCON): Dietary intervention (see below)
• 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)
• 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%.

Inclusion criteria

Diagnosed with diabetes type 2 and/or HbA1c ≥ 48 mmol/mol if no treatment with anti-diabetic medication and/or use of antidiabetic medication

Caucasian

No diagnose of Type 1 diabetes, mature onset diabetes of the young, Latent autoimmune diabetes of adults

T2D 0-6 years of duration

No treatment with insulin

Body Mass Index (BMI) >27 kg/m2 and <40 kg/m2

No known or signs of intermediate or severe microvascular complications to diabetes (retino-, neuro- or nephropathy)

No known cancer

No Known lung disease

No known cardiovascular disease

No known thyroid disease

No known liver disease

No known autoimmune disease

No other endocrine disorder causing obesity

No current treatment with anti-obesity medication

No current treatment with anti-inflammatory medication

No weight loss of > 5kg within the last 6 months

No diagnose of depression or treatment with anti-depressive medication, ongoing or within the last three months before enrolment

No diagnose of psychiatric disorder or treatment with anti-psychotic medication

No history of suicidal behavior or ideations within the last three months before enrolment

No previous surgical treatment for obesity (excluding liposuction > 1 year prior to enrolment)

Not pregnant/considering pregnancy

No functional impairments that prevents the performance of intensive exercise

Accept of medical regulation by the U-TURN endocrinologist

Inactivity, defined as < 1,5 hours of structured physical activity pr. week at moderate intensity and cycling < 30 minutes/5 km pr. day at moderate intensity (moderate intensity = out of breath but able to speak)

No participation in other research intervention studies

Exclusion criteria

HbA1c: >=75 mmol/mol with no glucose lowering medications

HbA1c: >=64 mmol/mol with mono glucose lowering therapy (if compliant with the prescription)

HbA1c: >=57 mmol/mol with >=dual glucose lowering therapy (if compliant with the prescription)

estimated glomerular filtration rate<60 mL/min

Protein or glucose in the urine at pre-screening

No biochemical sign of other major diseases

Presence of circulating glutamate-decarboxylase anti body (GAD) 65

Objective findings that contraindicates participation in intensive exercise

Anamnestic findings that contraindicates participation in the study

Unable to allocate the needed time to fulfill the intervention

Language barrier, mental incapacity, unwillingness or inability to understand and be able to complete the interventions