Abstract

Background: Long-lasting hyperglycemia in type 1 diabetic patients induces permanent alterations of endothelial function, by increased oxidative stress, even when glycemia is normalized.

Methods and Results: In this study 36 type 1 diabetic patients and 12 controls were enrolled. The diabetic patients were divided in three groups. The first group was treated for 24h with insulin, achieving a near-normalization of glycemia. At the 12 h of this treatment vitamin C was added for the remaining 12h. The second group was treated for 24h with vitamin C. At the 12 h of this treatment insulin was started, achieving a near-normalization of glycemia for the remaining 12h. The third group was treated for 24h with both vitamin C and insulin, achieving near normalization of glycemia. The same protocols were run after 1 month of Telmisartan or placebo. Neither normalization of glycemia or vitamin C treatment alone was able to normalize endothelial dysfunction or oxidative stress. Combining insulin and vitamin C normalized endothelial dysfunction and decreased oxidative stress to normal level. Telmisartan significantly improved basal endothelial function and decreased nitrotyrosine plasma levels. In patients treated with Telmisartan a near normalization of both flow mediated vasodilation and oxidative stress was achieved when glycemia was normalized, while adding vitamin C infusion did not show further effect on endothelial function or nitrotyrosine plasma levels.

Conclusions: These data indicate that combining the normalization of glycemia with an antioxidant can normalize endothelial function in type 1 diabetic patients and that Telmisartan works as antioxidant as vitamin C.