Six months of aerobic exercise does not improve microvascular function in type 2 diabetes mellitus

Aims/hypothesis Adults with type 2 diabetes mellitus have impaired microvascular function. It has been hypothesised that microvascular function may be restored through regular exercise. The aim of this study was to investigate whether 6 months of regular aerobic exercise would improve microvascular function in adults with type 2 diabetes. Materials and methods Fifty-nine patients with type 2 diabetes (32 males, age 62.9 +/- 7.6 years, HbA(1c) 6.8 +/- 0.9%) were randomised to either a 6-month aerobic exercise programme (30 min, three times a week, 70-80% of maximal heart rate) or a 'standard care' control group. Before and after the intervention period, microvascular function was assessed as the maximum skin hyperaemia to local heating and endothelial and non-endothelial responsiveness following the iontophoretic application of acetylcholine and sodium nitroprusside. Maximal oxygen uptake, as an index of aerobic fitness, was assessed using a maximal exercise test. Results No significant improvement was seen in the exercise group compared with the control group for any of the variables measured: maximal oxygen uptake (control pre: 1.73 +/- 0.53 [means +/- SD] vs post: 1.67 +/- 0.40; exercise pre: 1.75 +/- 0.56 vs post: 1.87 +/- 0.62 l/min, p=0.10); insulin sensitivity (insulin tolerance test) (control pre: -0.17 +/- 0.06 vs post: -0.17 +/- 0.06; exercise pre: -0.16 +/- 0.1 vs post: -0.17 +/- 0.07 mmol l(-1) p min(-1), p=0.97); maximal hyperaemia (control pre: 1.49 +/- 0.43 vs post: 1.52 +/- 0.57; exercise pre: 1.42 +/- 0.36 vs post: 1.47 +/- 0.33 V, p=0.85); peak response to acetylcholine (control pre: 1.37 +/- 0.47 vs post: 1.28 +/- 0.37; exercise pre: 1.27 +/- 0.44 vs post: 1.44 +/- 0.23 V, p=0.19) or to sodium nitroprusside (control pre: 1.09 +/- 0.50 vs post: 1.10 +/- 0.39; exercise pre: 1.12 +/- 0.28 vs post: 1.13 +/- 0.40 V, p=0.98). Conclusions/interpretation In this group of type 2 diabetic patients with good glycaemic control a 6-month aerobic exercise programme did not improve microvascular function or aerobic fitness.