Type 2 diabetes mellitus and its renal complications in relation to apolipoprotein E gene polymorphism

The apolipoprotein E (APOE) ε2 allele is reported to be associated with greater risk of renal impairment in type 2 diabetes. Relationships among APOE polymorphisms, renal impairment, and biochemical parameters were explored. A prospective study of 405 consenting Chinese type 2 diabetic patients [mean age ± standard deviation (SD): 59.2 ± 10.3 years] without advanced complications at entry was conducted. APOE genotyping and measurement of plasma biomarkers of oxidative stress and antioxidants were performed at entry. HbA1C, plasma glucose, lipids, creatinine, urine albumin/creatinine, and blood pressure were measured at entry and at up to 4 years of follow-up. APOE allelic frequencies were in Hardy−Weinberg equilibrium. Odds ratios of albuminuria at entry and/or during follow-up for different APOE groups were not significantly different. The non-ε2 (ε3/3, ε3/4, ε4/4) group had significantly greater plasma ascorbate (51.6 ± 20.1 μmol/L) than the ε2 (ε2/2, ε2/3) group (44.5 ± 16.2 μmol/L, P = 0.021), but higher plasma ascorbate levels did not seem to decrease the risk of renal impairment in the non-ε2 group. Baseline plasma lipid-standardized α-tocopherol levels were least in ε2 subjects with persistent albuminuria (3.6 ± 1.1 μmol/mmol of total cholesterol plus triglycerides, P = 0.008) compared with ε2 subjects who had no albuminuria at entry or during follow-up (4.5 ± 0.8 μmol/mmol of total cholesterol plus triglycerides). The APOE ε2 allele does not seem to be associated with increased risk of renal impairment in Chinese type 2 diabetic patients. Plasma lipid-standardized α–tocopherol may play a role in determining risk of renal dysfunction in type 2 diabetes.