Telmisartan shows an equivalent effect of vitamin C in further improving endothelial dysfunction after glycemia normalization in type 1 diabetes.
OBJECTIVE
Long-lasting hyperglycemia in type 1 diabetic patients induces permanent alterations of endothelial function by increased oxidative stress, even when glycemia is normalized.


METHODS
In this study, 36 type 1 diabetic patients and 12 control subjects were enrolled. The diabetic patients were divided into three groups. The first group was treated for 24 h with insulin, achieving a near normalization of glycemia. After 12 h of this treatment, vitamin C was added for the remaining 12 h. The second group was treated for 24 h with vitamin C. After 12 h of this treatment, insulin was started, achieving a near normalization of glycemia for the remaining 12 h. The third group was treated for 24 h with both vitamin C and insulin, achieving near normalization of glycemia. The same protocols were performed after 1 month of telmisartan or placebo.


RESULTS
Neither normalization of glycemia nor 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 levels. 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, whereas 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 an antioxidant like vitamin C.
Ceriello
Antonio
A
Centre of Excellence in Diabetes and Endocrinology, University Hospital of Coventry and Warwickshire, Warwick Medical School, University of Warwick, Coventry, UK. antonio.ceriello@warwick.ac.uk
Piconi
Ludovica
L
Esposito
Katherine
K
Giugliano
Dario
D
D047228:Angiotensin II Type 1 Receptor Blockers / Q000627:therapeutic use; D000975:Antioxidants / Q000494:pharmacology / Q000627:therapeutic use*; D001205:Ascorbic Acid / Q000494:pharmacology / Q000627:therapeutic use*; D001562:Benzimidazoles / Q000494:pharmacology / Q000627:therapeutic use*; D001565:Benzoates / Q000494:pharmacology / Q000627:therapeutic use*; D003922:Diabetes Mellitus, Type 1 / Q000150:complications / Q000188:drug therapy*; D004730:Endothelium, Vascular / Q000187:drug effects; D006801:Humans; D006943:Hyperglycemia / Q000188:drug therapy; D007004:Hypoglycemic Agents / Q000627:therapeutic use; D007328:Insulin / Q000627:therapeutic use; D018384:Oxidative Stress / Q000187:drug effects; D000077333:Telmisartan; D014652:Vascular Diseases / Q000188:drug therapy* / Q000209:etiology
D047228:Angiotensin II Type 1 Receptor Blockers; D000975:Antioxidants; D001562:Benzimidazoles; D001565:Benzoates; D007004:Hypoglycemic Agents; D007328:Insulin; D001205:Ascorbic Acid; D000077333:Telmisartan