Role of plasma ascorbate in diabetic microangiopathy.

Plasma total ascorbate status measured by 2.4 dinitrophenyl hydrazine method showed that diabetics (N = 100) had significantly lower plasma total ascorbate compared with 45 age and sex matched non-diabetic controls; 0.34 +/- 0.16 mg/dl vs 0.68 +/- .06 mg/dl, P less than 0.001) regardless of presence or absence of retinopathy and irrespective of mode of treatment. The finding unique to this study was that plasma total ascorbate status in diabetics with retinopathy (0.19 +/- 0.07 mg/dl) was significantly lower than that of uncomplicated diabetics (0.49 +/- 0.06 mg/dl; P less than 0.001). Plasma Glucose had no correlation with plasma ascorbate levels and effect of duration of Diabetes Mellitus (DM) on ascorbate status in diabetics was ambiguous. Diabetics had abnormally fragile cutaneous capillaries detected by Hess test. The incidence of capillary fragility was more in patients with retinopathy. Hess test can be used as an easy and non-invasive test to assess plasma ascorbate status to detect microvascular involvement in DM. The experience of this study reflects that the two distinct microvascular lesions in diabetes, i.e. abnormal dermal capillary fragility and retinopathy may have a common link to ascorbic acid deficiency. An early switching on of the supplementation of ascorbic acid may retard the development of microvascular complications in diabetes.