Two types of exercise have been extensively examined in T2D: endurance training and resistance training. It is widely held that exercise in general has many health benefits for individuals with T2D, and it has been known for many decades that muscle contraction stimulates glucose uptake by cells. Notwithstanding, variable responses to aerobic exercise training have been reported by several groups. Indeed, roughly 20% of subjects can be considered as ‘non-responders’ to exercise training as seen by endpoints such as changes on VO2 max, fasting glucose, body weight and insulin sensitivity.
Some authors have suggested that intersubject variability in restoring glycaemic control following exercise might be explained mainly by changes in insulin secretion1. In fact, a decreased capacity to secrete insulin may be related to the profound degree of glucotoxicity that exists in subjects with T2D, and glucotoxicity also predicts poorer training induced increases in ß-cell function. However, other factors should also be considered such as meal timing and time of day, as for example peak performance depends on the circadian phenotype. There may also be effects of drugs such as metformin on exercise, and exercise is also known to induce changes in the gut microbiome. Thus, response variability to exercise may be explained by a range of factors.