Mitochondrial Metabolism and Oxidative Stress in Function of the Physical Exercise and Nutritional Counseling in T2DM

Mitochondrial Metabolism and Oxidative Stress in Function of the Type of Physical Exercise and Nutritional Counseling in Type 2 Diabetes Mellitus

The goal of this randomized controlled trial is to learn about the effects of different aerobic modalities (moderate-intensity continuous training (MICT) and high-intensity interval training (HIIT)) and diet on mitochondrial properties and oxidative stress in patients with type 2 diabetes (T2D). It will also learn about the different effects of these interventions in men and women. The main questions it aims to answer are:

• What is the isolated and combined effect of these exercise modalities and diet? Is there a superior approach for mitochondrial metabolism and oxidative stress in patients with T2D?
• Is there a sex-specific best combination choice for these different interventions?
• Is there any relation between exercise and diet-induced changes in mitochondrial properties and oxidative stress and other health-related outcomes such as body composition or insulin sensitivity?

To answer these questions, researchers designed a two-factor study. One factor was exercise, which had three levels (MICT, HIIT, and the inactive (INACT) condition). The second factor was diet, with two levels (Diet (D) and no diet (ND)). Hence, participants were randomly allocated into 6 groups: INACT-ND, INACT-D, MICT-ND, MICT-D, HIIT-ND, and HIIT-D.

Participants did:

• Underwent a 12-week intervention within the condition of his/her group
• Visit the research group facilities three times per week if in an exercise group or once every two weeks if in a diet group.

This is a randomized controlled trial conducted in the Province of Cádiz (Spain). A total of 146 participants were enrolled in the study and underwent baseline and post-intervention determinations of the study outcomes. Just after the baseline determination, participants were randomly allocated to one of the aforementioned study groups. The randomization process was stratified by sex, which means that approximately 50% of participants in each group were women. All participants received detailed written and verbal information about the study objectives, procedures, benefits, and potential risks before providing written informed consent. This study adhered to the principles of the Declaration of Helsinki and was approved by the Provincial Research Ethics Committee of Cádiz and the Coordinating Committee of Biomedical Research Ethics of Andalucía (registration number 92.21; PEIBA number 1026-N-21; internal codes SICEIA-2025-001870 and SICEIA-2025-000778).

At both baseline and post-intervention, participants were scheduled in the morning following an overnight fast of 8-10 hours. They were instructed to maintain their usual lifestyle, abstain from alcohol and caffeine for 24 hours, and avoid strenuous physical activity for 72 hours prior to testing. Procedures included body composition assessment through electrical bioimpedance, a vastus lateralis muscle biopsy, fasting blood collection, and an oral glucose tolerance test (OGTT) by ingesting 75 grams of glucose and blood draws at 30, 60, 90, 120, 150, and 180 minutes post-ingestion. The same protocol was repeated after the 12-week intervention, with exercise groups completing their final training session at least 72 hours before the post-intervention assessments.

Inclusion Criteria:

• Diagnosis of T2D or prediabetes (glycated hemoglobin ≥ 5.7%)
• No history of substance abuse (tobacco, alcohol, or other drugs).
• Body mass index ≥25 kg/m², maintaining the habitual dietary patterns with stable body weight for at the least 6 months
• Stable physical activity and medication regimen for at least 6 months
• Not insulin-dependent
• Absence of injury, disease, disability, or other known medical condition which could affect the ability to successfully participate in physical exercise tests
• Absence of tumours and cancer disease
• Absence of other pathologies that could affect the study outcomes.
• Not under medication regimen that could affect the study outcomes.
• Being able to understand a communication in Spanish or English.
• Not pregnant

Exclusion Criteria:

• Failure to attend more than 2 consecutive or a total of 4 sessions of nutritional intervention.
• Failure to attend more than 4 consecutive or a total of 6 sessions of physical training.
• Serious injury
• Voluntary withdrawal
• Increased dose of diabetes medication