Influence of Acute Bouts of Exercise on Blood Glucose in Type 2 Diabetic Patients, as Measured by Continuous Glucose Monitoring Systems

Literature data indicate that the effect on blood glucose levels of a single bout of exercise may persist up to 48-h after cessation of exercise. Regular exercise improves insulin sensitivity and blood glucose control in subjects with type 2 diabetes and is considered a key element in the management of this condition. However, adaptive responses to exercise are altered in diabetic subjects and medications used in these patients may cause inappropriate insulin levels for the concurrent blood glucose concentrations, with a possible increase in risk for hypoglycaemia. Recently, the development and clinical availability of systems for the continuous monitoring of glucose (continuous glucose monitoring system, CGMS), have made it possible to continuously record blood glucose levels for several days in real life conditions, showing that possible differences in blood glucose levels of these individuals may occur during and after a single bout of exercise, depending on the characteristics of the physical activity. In particular, differences between aerobic vs resistance exercise and between low-intensity vs high-intensity exercise have been reported. However, there are only a few, small heterogeneous studies on this topic, and results are to some extent discordant, limiting any conclusions. Further research on this issue is needed before we can reach clear conclusions. In particular, the role of differences in frequency, duration, intensity, type and timing of exercise needs to be carefully investigated. Hopefully, this information will assist clinicians and exercise specialists in designing personalized exercise programmes and strategies aimed at optimally improving glucose control of type 2 diabetic patients, also limiting the risk for hypoglycaemia. In this article, we review the literature regarding the acute effect of different types of exercise on glucose levels, as measured by CGMS, in subjects with type 2 diabetes.