OBJECTIVE An association of the C-857T polymorphism of the tumor necrosis factor-alpha (TNF-alpha) gene promoter region with LDL cholesterol levels has been reported. This study was designed to evaluate the relationship between the TNF-alpha-C-857T polymorphism and LDL cholesterol levels according to statin treatment in subjects with type 2 diabetes. RESEARCH DESIGN AND METHODS DNA was obtained from 322 Japanese subjects (160 male and 162 female) with type 2 diabetes, and TNF-alpha-C-857T polymorphisms were determined by direct sequencing. Serum LDL cholesterol was measured by a direct method. RESULTS Although serum LDL cholesterol levels were significantly higher in the T carriers (C/T + T/T) than in the non-T carriers (C/C) (3.14 +/- 0.86 vs. 2.89 +/- 0.75 mmol/l, P < 0.05), there was no difference in LDL cholesterol levels between the non-T carriers and the T carriers in statin-untreated subjects (2.87 +/- 0.73 vs. 2.89 +/- 0.76 mmol/l, NS), whereas in statin-treated subjects, LDL cholesterol levels were significantly higher in the T carriers than in the non-T carriers (3.43 +/- 0.89 vs. 2.90 +/- 0.78 mmol/l, P = 0.0007). There were no differences in HDL cholesterol and triglyceride levels between the non-T carriers and the T carriers in both statin-treated and -untreated subjects. The percent decrease in LDL cholesterol levels after administration of statins was significantly smaller in the T carriers compared with the non-T carriers (27.6 vs. 36.4%, P = 0.031). CONCLUSIONS The mutant allele of the C-857T promoter polymorphism of the TNF-alpha gene may predispose to resistance to the LDL cholesterol-lowering effect of statins and could be one of the markers used to predict the efficacy of statins.