Effects of a Combined Exercise Intervention on the Gut Microbiome of People With Type 2 Diabetes

It is unclear if performing aerobic training (AT) and resistance training (RT) at a higher intensity in people with type 2 diabetes mellitus (T2DM) would generate greater improvement in HbA1c and if this would be associated with increased gut microbiome diversity.

Therefore, the objective of this study is to test whether performing resistance training and aerobic exercise (RT+AT) at a high intensity for 16 weeks will significantly improve glycemic control (HbA1c) and if this change is associated with an increase in gut microbiome diversity compared to performing RT+AT at a moderate intensity in individuals with poor glycemic control. We hypothesize that individuals performing RT+AT at a high intensity will significantly reduce HbA1c and improve gut microbiome diversity compared to individuals performing RT+AT at a moderate intensity.

Methods: This study is a parallel-group, single-blinded, randomized trial including 40 adults (50% males and females) living with T2DM. Participants will be allocated to one of two treatment groups: 1) high intensity or 2) moderate intensity for 16 weeks.

A total of 40 participants (n = 20 for each sex) living with T2DM with poor glycemic control (HbA1c => 7.0%), aged between 19-64 years, who do not currently meet the recommended levels of physical activity for optimal health, (i.e., 150 min of moderate-to-vigorous physical activity + 2 days/week of resistance training) will be recruited.

Intervention: Participants will undergo a supervised exercise intervention of RT+AT for 16 weeks, performed at high or moderate intensity. 1) High intensity: AT will be performed at 70-80% heart rate reserve and 8-10 repetitions (75-80% maximal strength). 2) Moderate intensity: AT will be performed at 45-55% heart rate reserve and 12-15 repetitions (65-70% maximal strength). AT will consist of expending 10 kcal/kg per week, while RT will consist of 2 days of resistance training per week as per the recommendations. Our previous work shows that participants could perform this type of intensity; therefore, no problems are anticipated. Exercise intensity will be monitored using heart rate for aerobic training and the OMNI-RES scale (1-10) for resistance training.

Primary Outcomes: All HbA1c tests will be performed using a validated DCA Vantage® Analyzer (Siemens, Germany). Participants will undergo HbA1c tests at baseline and post-intervention (16 weeks). The gut microbiome composition will be determined at baseline and post-intervention in participant feces using next-generation sequencing (Illumina MiSeq) of 16S ribosomal RNA genes.

Inclusion criteria

• Adults aged 19 - 64 years old;
• Diagnosed with type 2 diabetes;
• An HbA1c >= 7.0%;
• Not currently meeting the recommended levels of physical activity for optimal health (i.e., 150 minutes of moderate-to-vigorous physical activity and 2+ days/week of resistance training);
• Average less than 10,000 steps per day over the last seven days;
• No change in diabetes medications over the last three months.

Exclusion criteria

• Not diagnosed with type 2 diabetes;
• Partaking in a self-reported regular exercise regimen, defined as consistent participation in running or jogging activity, attending exercise classes every week, or averaging 10,000 steps per day or more over seven days;
• Currently performing two days of resistance training per week;
• Having an injury that would prevent safe participation in the intervention;
• A self-reported diagnosis of low iron concentrations, anemia, or being treated for these conditions;
• A diagnosis of any red blood cell altering condition (i.e., sickle cell anemia, poikilocytosis);
• Currently living with any cardiovascular disease which would impact the ability to participate in exercise safely;
• Currently prescribed any medication which would impact the ability to use a heart rate monitor to accurately track intensity.