Public health officials and healthcare providers commonly recommend exercise as a strategy to prevent or manage the symptoms of type 2 diabetes, but the cardiometabolic response to exercise is variable. Whereas exercise improves insulin sensitivity and promotes cardiovascular health in most adults (responders), exercise exerts a paradoxical effect in which metabolic health is compromised in as many as 69 percent of adults (non-responders). Findings from a recent study suggest the variable effects of exercise in people with prediabetes may be due to alterations in gut microbial fermentation.
Microbial fermentation is the process by which gut bacteria break down and utilize carbohydrates in the gut. The metabolites produced during microbial fermentation include short-chain fatty acids and branched-chain amino acids, which are absorbed and used by the host. Short-chain fatty acids improve symptoms of diabetes, but branched-chain amino acids have the converse effect
The study involved both humans and mice. The human study included 39 overweight or obese men with prediabetes who were between the ages of 20 and 60 years. Participants were randomized to engage in either sedentary activities or supervised exercise training for 12 weeks. They maintained their usual diet throughout the study period. At the end of the 12-week period, fecal microbial samples from two of the participants (responders and non-responders) were transplanted into obese mice.
The results demonstrated that the responders' microbiota displayed increased production of short-chain fatty acids, whereas those of the non-responders displayed increased production of brain-chain amino acids. Fecal microbial transplantation from responders mimicked the effects of exercise on alleviation of insulin resistance in the mice, but fecal transplants from the non-responders did not. These findings may augment and facilitate clinical management of symptoms of diabetes.