Exercise Training and Type 2 Diabetes

Background

In recent years, there's been heightened awareness of chronic diseases like type 2 diabetes mellitus (T2DM) and their global impact. T2DM has surged dramatically, with cases quadrupling in the last 30 years. The International Diabetes Federation estimates 451 million cases globally, with projections indicating a rise to 629 million by 2045. In high-income countries, T2DM prevalence peaks in older age groups, and a study from the Faroe Islands shows the same tendency. T2DM is characterized by insulin resistance (often associated with visceral obesity), abnormal insulin secretion, and elevated blood glucose levels. It significantly increases the risk of cardiovascular disease, which is the leading cause of death among T2DM patients.

Studies on T2DM patients demonstrate that 2-3 months of regular aerobic training leads to a significant reduction in visceral fat, ranging from 27% to 45% in men and women. Additionally, physical exercise improves glycemic control, with postprandial blood glucose lowered after aerobic, resistance, or combined training. Combination training, including aerobic and resistance exercises or team sports, is recommended for T2DM patients, offering optimal benefits. High-intensity interval training has shown efficiency in blood glucose regulation. Intensive lifestyle interventions in T2DM patients can markedly improve regulation and increase the likelihood of partial remission compared to general diabetes support programs. Small-sided football game studies demonstrate beneficial effects on fasting plasma glucose and complication markers. Physical fitness protects against all-cause mortality and cardiovascular death. Even low-volume physical activity is associated with a significant reduction in the relative risk of noncommunicable diseases. Recent studies suggest that complex training modes like team sports can provide broad-spectrum health effects, even with volumes lower than WHO recommendations.

Standard treatment for T2DM typically includes dietary guidance and advice on a healthy lifestyle. Medical therapy often includes metformin tablets, a Glucagon-Like Peptide-1 (GLP-1) receptor agonist, and/or a sodium-glucose cotransporter-2 (SGLT-2) inhibitor, and insulin. A large portion of T2DM patients on the Faroe Islands are undergoing GLP-1 receptor agonist or SGLT-2 inhibitor treatment. Studies have shown that these medications are highly effective in improving glucose levels and promoting weight loss. The weight loss mainly involves a decrease in fat mass. However, a review has revealed that the reduction in lean body mass accounts for 20% to 50% of the total weight lost, aligning with weight loss observed with dietary changes and bariatric surgery. Therefore, it is also important to investigate to what extent the positive impact of hybrid training is influenced by GLP-1 receptor agonist and SGLT-2 inhibitor treatment.

Hypothesis

The primary hypothesis is that hybrid training (football) combining endurance, high-intensity interval, and resistance training improves general health status, blood glucose regulation, and muscle metabolism, as well as well-being in patients with T2DM. An exploratory hypothesis is that these changes occur irrespective of GLP-1 receptor agonist and SGLT-2 inhibitor treatment.

Methods

Men and women aged 40-70 diagnosed with T2DM within the last 10 years will be invited. Individuals with severe micro- or macrovascular complications and lactating or pregnant women will be excluded, as further detailed in the full protocol. Extraction from the electronic patient records indicates that approximately 800 individuals meet the criteria.

The study will be designed as a randomized control trial with small-sided football playing as the intervention. In the randomization, there will be stratification based on age (≥55 yrs/<55 yrs), gender (male/female) and whether the individuals are undergoing treatment with a GLP-1 receptor agonist or not (treatment/non-treatment). Patients will go through a test battery before (pre-tests) they are randomized into either a football group (FG) or a control group (CG) who will receive standard treatment. After the intervention, participants will undergo the same test battery (post-tests) for evaluation.

Test battery: blood pressure, blood parameters such as HbA1c, plasma glucose, C-peptide, total cholesterol, high-density lipoprotein cholesterol (HDL-C), low-density lipoprotein cholesterol (LDL-C) and triglycerides, as well as systemic markers of inflammation, bone turnover markers, and urine albumin-to-creatinine ratio test. Body composition will be assessed by dual-energy X-ray absorptiometry (DXA) scans of body fat content, lean body mass, and bone mineralization. The patients will perform a Peak oxygen uptake test on a cycling ergometer as well as a Yo-Yo Intermittent Endurance test level 1 (Yo-Yo IE1) to determine physical fitness. To exclude severe peripheral neuropathy, vibration sensation in the feet will be measured using a biothesiometer along with the pre-tests.

To assess the 24-hour glucose profile, all participants in FG and CG will be provided with a blinded Continuous Glucose Monitoring system (CGM) with two sensors, each designed to last for 14 days. These sensors will be worn consecutively during the initial and final 14 days of the intervention period.

Finally, muscle biopsies will be obtained from a random subset of participants allocated to the FG (10 males and 10 females treated with GLP-1 and 10 males and 10 females not treated with GLP-1) in order to assess the potential impact of GLP-1 on training-induced adaptations in skeletal muscle.

Intervention

The FG group will train in small-sided football games for 60 minutes minimum three times per week for 14 weeks. Training will be intensified from walking football to small-sided game football (3v3-7v7) after two weeks, as described by Krustrup and Krustrup. Trained coaches will be responsible for the training sessions.

Perspective

Additional knowledge about the impact of hybrid training (football), combining endurance, high-intensity interval, and resistance training, on general health status, blood glucose regulation, muscle metabolism, and well-being in patients with T2DM, could form the basis for new recommendations in the treatment of this patient group. Furthermore, there is a need for a comprehensive understanding regarding the impact of hybrid training combined with GLP-1 receptor agonists and SGLT-2 inhibitor treatment in patients with T2DM.

Inclusion criteria

• Diagnosed with type 2 diabetes within ten years of study recruitment

Exclusion criteria

• Diabetic retinopathy (expect mild non-proliferative retinopathy or early proliferative retinopathy
• Macro-albuminuria (urine albumin-creatinine ratio ≥ 300 mg/g)
• Nepropathy (plasma creatinine ≥ 130 μM)
• Diabetic neuropathy (except mild affected vibratory testing (<50 V)
• History of ischemic heart disease
• History or signs of arterial insufficiency
• Steroid treatment within 3 months of baseline examination
• Thyroid disease
• Inability or contraindication to increased levels of physical activity
• Anaemia (haemoglobin < 7.3 mmol/L (women) and 8.3 mmol/L (men)
• Signs of kidney disease
• Pregnancy or breast feeding