IMPAIRED ENDOTHELIUM-DEPENDENT AND INDEPENDENT DILATATION OF FOREARM RESISTANCE ARTERIES IN MEN WITH DIET-TREATED NON-INSULIN-DEPENDENT DIABETES - ROLE OF DYSLIPIDEMIA

1. We measured endothelium-dependent and independent dilatation of for earm resistance arteries in 29 men with diet-treated non-insulin-depen dent diabetes mellitus and 18 age- and sex-matched control subjects, N one of the diabetic patients had hypercholesterolaemia, overt hyperten sion or microproteinuria. 2. We examined endogenous and exogenous nitr ic oxide-mediated vasodilatation by measuring forearm blood how with v enous occlusive plethysmography after administration of acetylcholine (7.5 and 15 mu g/min) and sodium nitroprusside (3 and 10 mu g/min), re spectively, into the brachial artery, N-G-monomethyl-L-arginine was al so infused to study the inhibition of basal and stimulated release of nitric oxide. 3. The vasodilatory response to acetylcholine, expressed as area under curve, was significantly decreased in the diabetic pati ents compared with the control subjects (P=0.019). N-G-monomethyl-L-ar ginine significantly reduced basal (P <0.001) and acetylcholine-stimul ated blood flow (P <0.02) in both groups, The vasodilatory response (a lso expressed as area under curve) to sodium nitroprusside was signifi cantly less (P=0.044) in the diabetic patients than in the control sub jects. 4. In the diabetic patients, impaired vasodilatory responses to acetylcholine were significantly correlated with higher serum triacyl glycerols (P=0.048) and lower high-density lipoprotein-cholesterol con centrations (P=0.007); the association with high-density lipoprotein w as independent of age, glycated haemoglobin and blood pressure, Sodium nitroprusside responses were not correlated with lipid and lipoprotei n concentrations. 5. We conclude that there is impaired endothelial an d smooth muscle cell function in men with diet-treated non-insulin-dep endent diabetes mellitus uncomplicated by overt hypertension or microp roteinuria. Endothelial dysfunction may be related to diabetic dyslipi daemia and associated metabolic disturbances.