Background: Variations of the apolipoprotein A5 (APOA5) gene are strongly associated with hypertriglyceridemia. Vitamin E is transported in triglyceride (TG)-rich lipoproteins and therefore could also be modulated by apoAV. Patients with type 2 diabetes have a tendency towards high TG values and increased oxidative stress.
Methods: We examined the impact of genetic APOA5 variation (-1131T-->C) on vitamin E and oxidative status in 169 non-smoker type 2 diabetic patients. Plasma samples were analyzed for lipids, lipoproteins, vitamin E, oxidized low-density lipoprotein (oxLDL), lipoperoxides, autoantibodies against oxLDL and diene formation of LDL.
Results: Vitamin E concentrations were higher in TC carriers compared with TT carriers (45.48+/-8.20 micromol/L vs. 40.32+/-10.47 micromol/L; p=0.02). The prevalence of the TC genotype was 2.6-fold higher among individuals with high vitamin E concentrations (p=0.02). The APOA5 polymorphism did not determine any differences in oxidative status. Fasting TG concentration was a significant 21% higher in carriers of the TC genotype (p=0.04) due to higher TG concentrations in very-low-density lipoprotein (VLDL) and high-density lipoprotein.
Conclusions: The APOA5-1131T-->C polymorphism is associated with both higher vitamin E concentrations and higher VLDL-TGs in diabetic patients.