Abdominal obesity and hyperinsulinemia are associated with abnormalities in lipid metabolism and are important risk factors for coronary artery disease. Because hyperinsulinemia frequently accompanies abdominal obesity, it is unclear whether each is independently related to lipid abnormalities. Dietary saturated fat may influence these associations since it is associated with elevated lipid levels, obesity and hyperinsulinemia. Abdominal obesity (indexed as abdomen-to-hip circumference ratio), serum insulin level and dietary saturated fat intake were examined in relation to serum levels of lipids and lipoproteins in 878 male participants of the Normative Aging Study. Abdomen-to-hip ratio and insulin level were inversely related to high density lipoprotein cholesterol (HDL-C) (r = -0.17 and -0.21, respectively), and positively related to triglycerides (r = 0.25 and 0.36, respectively). Saturated fat intake was positively related to body mass index (r = 0.20), abdomen-to-hip ratio (r = 0.13), and insulin level (r = 0.10). In multiple linear regression models, abdomen-to-hip ratio was positively related to triglycerides and low density lipoprotein cholesterol (LDL-C) after adjusting for the effects of body mass index, alcohol intake, age, cigarette smoking and physical activity level, but was not significantly related to HDL-C. When serum insulin level was included as a covariate, abdomen-to-hip ratio remained significantly related to LDL-C and triglycerides, although its relationship with triglycerides was attenuated. Insulin level remained inversely related to HDL-C and triglycerides in multivariate models which adjusted for the effects of abdomen-to-hip ratio and BMI.(ABSTRACT TRUNCATED AT 250 WORDS)