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

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.

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.

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 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).

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.