Effect of oral vitamin E (alpha-tocopherol) supplementation on vascular endothelial function in Type 2 diabetes mellitus.
OBJECTIVE
Vascular endothelial dysfunction, an early marker of atherosclerosis, has been demonstrated in Type 2 diabetes mellitus (DM). Vitamin E preserves endothelial function in animal models of diabetes and reduces cardiovascular risk. We examined endothelial function and the effect of vitamin E supplements in uncomplicated Type 2 DM.


METHODS
Forty-eight subjects with Type 2 DM and 21 controls had endothelial function assessed using forearm venous occlusion plethysmography with endothelium-independent (sodium nitroprusside) and dependent (acetylcholine, bradykinin) vasodilators. Those with diabetes received 1600 i.u. daily oral alpha-tocopherol or placebo, double-blind for 8 weeks, and had endothelial function reassessed.


RESULTS
The diabetic group had higher HbA1c (6.9+/-1.4 vs 4.8+/-0.6%; P<0.01) and systolic (145+/-15 vs. 130+/-16 mm Hg; P<0.01) but not diastolic blood pressure (79+/-8 vs. 76+/-9 mm Hg; P = 0.15). There was blunted vasodilation to acetylcholine (15 microg/min; P<0.01) in subjects with diabetes. Vasodilation to sodium nitroprusside and bradykinin was similar (all P>0.1). Alpha-tocopherol did not affect vasodilation to nitroprusside (P>0.1), acetylcholine (P>0.1) or bradykinin (P>0.1).


CONCLUSIONS
There may be receptor-specific endothelial dysfunction in subjects with uncomplicated Type 2 DM. This is not improved by treatment with alpha-tocopherol.
Gazis
A
A
Department of Therapeutics and Diabetes, University Hospital, Nottingham, UK.
White
D J
DJ
Page
S R
SR
Cockcroft
J R
JR
D000284:Administration, Oral; D016022:Case-Control Studies; D003924:Diabetes Mellitus, Type 2 / Q000188:drug therapy* / Q000503:physiopathology; D019587:Dietary Supplements; D004311:Double-Blind Method; D004730:Endothelium, Vascular / Q000503:physiopathology*; D005260:Female; D005542:Forearm / Q000098:blood supply; D006801:Humans; D008297:Male; D008875:Middle Aged; D012039:Regional Blood Flow / Q000187:drug effects; D014810:Vitamin E / Q000627:therapeutic use*
D014810:Vitamin E