Safety and magnitude of changes in blood glucose levels following exercise performed in the fasted and the postprandial state in men with type 2 diabetes

Abstract

Background

Information on the extent to which acute exercise reduces blood glucose levels (BGL) in type 2 diabetes is lacking. For this reason, the effects of exercise initiated at different preexercise BGL were assessed in men with type 2 diabetes both in the fasted (FS) and the postprandial states (PS).

Design and methods

Forty-three men with type 2 diabetes, 12 on diet alone and 31 on hypoglycaemic agents, completed a total of 1555 exercise sessions performed in the FS and 0-1, 1-2, 2-3, 3-4, 4-5, and 5-8 h in the PS. Capillary BGL were measured before and immediately after a 1h standardized aerobic exercise session on an ergocycle at 60% of Vo₂ peak. Results In the FS, there was an increase in postexercise BGL of 27 ± 21% (mean±SD; P < 0.001) when preexercise BGL was ≤ 6 mmol/l, no change when preexercise BGL were between 6 and 8 mmol/l, and a significant decrease of 12 ± 13% when preexercise BGL were >8 mmol/l (P < 0.001). In the PS, most exercise sessions were associated with significant decreases in BGL ranging between 18 ± 17 and 50 ± 12% (P < 0.001), depending on the time interval between meals and the onset of exercise. Regarding the metabolic PS, the decline in BGL was most pronounced with high preexercise BGL.

Conclusions

Our observations not only demonstrate that it was safe for middle-aged obese men with type 2 diabetes to exercise in the FS, but also show that the decrease in BGL during aerobic exercise was largely dependent on preexercise BGL. Eur J Cardiovasc Prev Rehabil 14: 831-836 © 2007 The European Society of Cardiology