Effects of improved glycaemic control on endothelial function in patients with type 2 diabetes

BACKGROUND: Patients with type 2 diabetes have abnormal endothelial function but it is not certain whether improvements in glycaemic control will improve endothelial function. AIMS: To examine the effects of short-term improved glycaemic control on endothelial function in patients with inadequately regulated type 2 diabetes mellitus. METHODS: Forty-three patients with type 2 diabetes and glycosylated haemoglobin (HbA1c) > 8.9% were randomized to either improved glycaemic control (IC) n = 21 or usual glycaemic control (UC) n = 22 for 20 weeks. Using high-resolution B-mode ultrasound, brachial artery flow-mediated dilatation (FMD) and glyceryl trinitrate-mediated dilatation (GTN-D) were measured at baseline and 20 weeks later. RESULTS: After 20 weeks, HbA1c was significantly lower in IC versus UC (IC 8.02 +/- 0.25% versus UC 10.23 +/- 0.23%, P < 0.0001) but changes in FMD and GTN-D were not different between the groups (FMD at baseline and week 20 IC 5.1 +/- 0.56% versus 4.9 +/- 0.56% and UC 4.2 +/- 0.51% versus 3.1 +/- 0.51%; P = 0.23: GTN-D IC 12.8 +/- 1.34% versus 10.4 +/- 1.32% and UC 13.7 +/- 1.2% versus 12.7 +/- 1.23%; P = 0.39). In the IC group weight increased by 3.2 +/- 0.8 kg after 20 weeks compared to 0.02 +/- 0.70 kg in UC (P = 0.003). Blood pressure and serum lipid concentrations did not change in either group. CONCLUSIONS: Short-term reduction of HbA1c levels did not appear to affect endothelial function in patients with type 2 diabetes and previously poorly regulated glycaemic control.