Effects of long-term supplementation with moderate pharmacologic doses of vitamin E are saturable and reversible in patients with type 1 diabetes.
BACKGROUND
Vitamin E supplementation has been proposed as adjunctive therapy to counteract the increased LDL oxidation in diabetes and thus prevent or delay cardiovascular complications.


OBJECTIVE
The objective of this study was to investigate the effect of a moderate pharmacologic dose of vitamin E for </=1 y in patients with type 1 diabetes.


METHODS
The study was double blind and the subjects were randomly assigned to 2 groups: the supplemented group (group S; n = 22) received 250 IU (168 mg) RRR-alpha-tocopherol 3 times/d for 1 y and the placebo group (group P; n = 22) received a placebo for 6 mo followed by 250 IU (168 mg) RRR-alpha-tocopherol 3 times/d for an additional 6 mo.


RESULTS
Serum vitamin E doubled after 3 mo of supplementation, from a mean (+/-SD) of 36.9 +/- 10.9 to 66.4 +/- 18.3 micromol/L (P: < 0.0005). Although lipid profiles, glycated hemoglobin, and blood biochemistry values did not change significantly, copper-induced in vitro peroxidizability of LDL and VLDL decreased after 3 mo of supplementation: the production of thiobarbituric acid-reactive substances decreased by 30-60% (P: < 0. 005) and the lag time for the appearance of fluorescent products increased from 107 +/- 25 to 123 +/- 30 min in group S (P: = 0.002 compared with group P). Vitamin E supplementation for an additional 3-9 mo resulted in no further changes in serum vitamin E and lipoprotein peroxidizability. Values returned to baseline after supplementation ended.


CONCLUSIONS
Because the improvement in lipoprotein peroxidizability is saturable and reversible, life-long supplementation with vitamin E should be considered in patients with type 1 diabetes.
Engelen
W
W
Laboratory of Endocrinology, the University of Antwerp, Antwerp, Belgium.
Keenoy
B M
BM
Vertommen
J
J
De Leeuw
I
I
D000328:Adult; D001786:Blood Glucose / Q000032:analysis; D015992:Body Mass Index; D003300:Copper / Q000494:pharmacology; D003922:Diabetes Mellitus, Type 1 / Q000097:blood* / Q000188:drug therapy; D019587:Dietary Supplements; D004311:Double-Blind Method; D005260:Female; D006442:Glycated Hemoglobin / Q000032:analysis; D006801:Humans; D007328:Insulin / Q000008:administration & dosage / Q000627:therapeutic use; D015227:Lipid Peroxidation / Q000187:drug effects; D008077:Lipoproteins, LDL / Q000097:blood; D008079:Lipoproteins, VLDL / Q000097:blood; D008297:Male; D008875:Middle Aged; D010919:Placebos; D017392:Thiobarbituric Acid Reactive Substances / Q000378:metabolism; D014810:Vitamin E / Q000008:administration & dosage* / Q000097:blood
D001786:Blood Glucose; D003300:Copper; D006442:Glycated Hemoglobin; D007328:Insulin; D008077:Lipoproteins, LDL; D008079:Lipoproteins, VLDL; D010919:Placebos; D017392:Thiobarbituric Acid Reactive Substances; D014810:Vitamin E