Impaired vascular function during short-term poor glycaemic control in Type 1 diabetic patients

Aim To study the effects of short-term poor glycaemic control on vascular function in Type 1 diabetic patients. Methods Ten Type 1 diabetic patients, with diabetes duration of less than 10 years and normal urinary albumin excretion and ophthalmoscopy, were studied. All patients were examined after 48 h of good vs. poor glycaemic control within a 3-week period. Blood glucose was measured seven times daily for 2 days before each examination. External ultrasound was used to measure the dilatory response of the brachial artery to post-ischaemic increased blood flow (endothelium-dependent dilation) and to nitroglycerin (endothelium-independent dilation). Plasma concentration of von Willebrand factor antigen, adhesion molecules, vascular endothelial growth factor, homocystein and cholesterol were also measured. Results The median blood glucose levels in the 48 h before the examinations were [median (range), good vs. poor control]: 6.3 (5.0-7.6) vs. 15.9 (11.3-17.8) (mmol/l). The flow-associated vasodilation (% of baseline) was reduced during poor control: 102.7 (94.7-110.8) vs. 104.0 (99.6-118.5) (P < 0.05) as were the nitroglycerin-induced dilation (% of baseline): 114.5 (103.3-127.9) vs. 120.2 (106.8-148.0) (P < 0.05). P-von Willebrand factor antigen was high during poor control (kIU/l): 1.14 (0.73-1.84) vs. 0.86 (0.72-1.39) (P < 0.05) and so was P-vascular endothelial growth factor (ng/l): 288 (133-773) vs. 254 (90-383) (P < 0.05). Conclusions Short-term (48 h) hyperglycaemia in Type 1 diabetic patients may disturb vascular function, possibly mediated through smooth muscle cell dysfunction as well as endothelial dysfunction. We suggest that prolonged and repeated episodes of hyperglycaemia could possibly lead to permanent vascular dysfunction and thereby development and progression of vascular complications in diabetes.