Relationship of blood thromboxane-B2 (TxB2) with lipid peroxides and effect of vitamin E and placebo supplementation on TxB2 and lipid peroxide levels in type 1 diabetic patients

OBJECTIVE - To study the effect of vitamin E supplementation on platelet hyperaggregability in type 1 diabetic patients. RESEARCH DESIGN AND METHODS - Written informed consent according to the Institutional Review Board on Human Experimentation guidelines was obtained from diabetic patients (n = 29) and their age-matched normal siblings (n = 21) to participate in this study; Diabetic patients were supplemented with DL-alpha-tocopherol (vitamin E) capsule (orally, 100 IU/day) or placebo for 3 months in a double-blind clinical trial. Alternate diabetic patients were assigned to vitamin E or placebo during regular visits to the clinic. Pasting blood was collected from each diabetic patient before the start and after the vitamin E or placebo supplementation. Platelet aggregability was assessed by competitive enzyme-linked immunosorbent assay of the blood TxB(2) (a stable thromboxane metabolite). Plasma vitamin E and MDA (malondialdehyde, a product of lipid peroxidation) was assessed by high-performance liquid chromatography Data were analyzed statistically on 12 diabetic patients on vitamin E and 12 on placebo supplementation. RESULTS - Diabetic patients (n = 29) had 62% higher (P < 0.05) levels of TxB(2) and 15% higher levels (P < 0.05) of MDA in comparison to normal subjects (n = 21). Plasma TxB(2) levels had a significant correlation with MDA levels (r = 0.45, P < 0.02) but not with the HbA(1) (r = -0.08), glucose (r = -0.13), duration of diabetes (r = -0.04), or age (r = 0.12) of diabetic patients. Vitamin E supplementation lowered MDA levels by 30% (P < 0.04), TxB(2) levels by 51% (P < 0.03), and triglyceride levels by 22% (P < 0.04) in diabetic patients. There were no differences in these parameters before versus after placebo supplementation. CONCLUSIONS - The elevated blood level of TxB(2) (hyperaggregability of platelets) is significantly related to the level of lipid peroxidation products (oxidative stress) in type 1 diabetic patients. Supplementation of modest doses of vitamin E (100 IU/day) significantly lowers blood TxB(2) and lipid peroxidation products levels in type 1 diabetic patients.