Endothelial dysfunction plays a key role in the pathogenesis of diabetic angiopathy in man. The biochemical basis of endothelial dysfunction in diabetic man, however, has yet to be fully elucidated.

Large artery stiffening could contribute to the development of cardiovascular disease. The aim of this study was to investigate associations between arterial stiffness and diameter with insulin sensitivity and body composition in healthy men and women. In healthy, young (< 41 years old), non-obese (BMI < 27 kg/m2) men (n = 17) and women (n = 17), we measured the arterial diameter, the distension, the distensibility coefficient and the compliance coefficient of the elastic common carotid and muscular femoral arteries with a non-invasive ultrasonographic method. We also assessed glucose uptake (by a euglycaemic hyperinsulinaemic clamp technique), total body fat and lean body mass (by bioelectrical impedance analysis) and abdominal subcutaneous and visceral fat area (by magnetic resonance imaging). In women, but not in men, the distension and distensibility and compliance coefficients of the femoral artery were negatively associated with insulin concentrations (beta = -0.62, p = 0.008; beta = -0.65, p = 0.005 and beta = -0.59, p = 0.01), and positively with glucose uptake (beta = 0.59, p = 0.02; beta = 0.68, p = 0.005 and beta = 0.54, p = 0.04). Associations with glucose uptake were independent of the mean arterial pressure and body composition. In men and women, arterial compliance was positively associated with fat mass variables, which were mediated by a strong association between the femoral artery diameter and lean body mass (beta = 0.80, p < 0.001) and between the common carotid artery diameter and visceral fat area (beta = 0.56, p = 0.001). We found an independent association between insulin resistance and arterial stiffness, which was more pronounced in women than in men.

Vascular complications in diabetes mellitus are associated with endothelial dysfunction. Whether endothelium-dependent vasodilation is impaired in normoalbuminuric patients with insulin-dependent diabetes mellitus (IDDM) is controversial. Using a noninvasive echo-Doppler method, we investigated endothelium-dependent and endothelium-independent vasodilation in the brachial artery of IDDM patients. There were 52 normoalbuminuric and normotensive patients with IDDM (aged 31.9 +/- 9.8 years; diabetes duration, 14.9 +/- 7.9 years; glycated hemoglobin, 7.9 +/- 1.2%) and 52 healthy control group (C) subjects comparable for age and sex studied. Brachial artery diameter was measured at baseline, during postocclusion reactive hyperemia (flow-mediated, endothelium-dependent dilation [FMD]), and after 400 micrograms glyceryl trinitrate (GTN) sublingually (endothelium-independent vasodilation). Vasodilation was expressed as the percentage change relative to the baseline diameter. Baseline flow and blood pressure were similar for IDDM patients and C. Baseline vessel diameter was slightly larger in IDDM patients (3.10 +/- 0.52 mm) compared with C (2.89 +/- 0.55 mm, P = 5.0). FMD in IDDM patients was decreased (12.0 +/- 9.1% versus 15.7 +/- 9.5% in C, P = .046), as was GTN-induced vasodilation (14.9 +/- 8.2% versus 18.3 +/- 8.5% in C, P = .045). After correction for the difference in baseline diameter, FMD and GTN-induced dilation were not different between the groups. GTN-induced vasodilation decreased slightly with increasing diabetes duration. There was no relation between the vasodilatory responses and HbA1c. In normoalbuminuric IDDM patients, endothelium-dependent as well as endothelium-independent vasodilation are normal when the difference in baseline diameter is taken into account.

We concluded that betaine is not effective in conjunction with folic acid in the treatment of hyperhomocysteinaemia in haemodialysis patients. Normalization of plasma total homocysteine is seldom achieved with 1, 5 or 15 mg folic acid daily, which may explain why long-term homocysteine-lowering treatment with 1 or 5 mg folic acid does not ameliorate endothelial function.

The results of the present study show that in this group of patients with uncomplicated IDDM, vessel wall properties of elastic and muscular large arteries were not obviously reduced when compared with healthy control subjects. However, distensibility of the FA was lower in IDDM patients. Early atherosclerotic changes in IDDM frequently occur at this site. A difference related to the duration of diabetes could not be excluded.