Does endurance training affect IGF-1/IGFBP-3 and insulin sensitivity in patients with type 2 diabetes?

The aim of the present study was to determine whether six weeks of submaximal endurance training using a cycle ergometer would result in a modified serum insulin-like growth factor-1 (IGF-1), an insulin-like growth factor binding protein 3 (IGFBP-3), and insulin resistance in middle-aged men with type 2 diabetes (T2D).

Twenty male patients with T2D voluntarily participated in this study and were randomly divided into two groups: the training group (N.=10) and the control group (N.=10). The training protocol consisted of a 45-minutes cycling session/day, three days/week for six weeks with intensity 60-70% of the maximum heart rate. To examine the IGF-1 and the IGFBP-3, fasting blood glucose levels, and insulin resistance, blood sampling was performed before and immediately after the first and 18th sessions. The homeostatic model assessment (HOMA-IR) method was used to determine insulin resistance.

Before the study began, no significant difference between the two groups was observed in the anthropometric and blood factors. After a session of aerobic exercise, IGF-1 and IGFBP-3 levels were significantly increased (153.79% and 64.3%, respectively), and fasting glucose and insulin resistance levels were significantly decreased (15.82% and 27.82%, respectively); however, the changes resulting from a six-week training period were not significant.

According to the present study, one session of aerobic exercise for middle-aged men with T2D leads to increased IGF-1 and IGFBP-3, and to decreased fasting glucose and insulin resistance. Considering the lack of changes after a six-week training, it seems that the amount of change depends on subjects' fitness level and exercise parameters. From a clinical point of view, the beneficial effects of acute exercise inT2D subjects show that such exercises should be part of the daily program for them.