THE RELATIONSHIPS OF ABDOMINAL OBESITY, HYPERINSULINEMIA AND SATURATED FAT INTAKE TO SERUM-LIPID LEVELS - THE NORMATIVE AGING STUDY

Abdominal obesity and hyperinsulinemia are associated with abnormaliti es in lipid metabolism and are important risk factors for coronary art ery 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 hyperi nsulinemia. Abdominal obesity (indexed as abdomen-to-hip circumference ratio): serum insulin level and dietary saturated fat intake were exa mined in relation to serum levels of lipids and lipoproteins in 878 ma le participants of the Normative Aging Study. Abdomen-to-hip ratio and insulin level were inversely related to high density lipoprotein chol esterol (HDL-C) (r = -0.17 and -0.21, respectively), and positively re lated to triglycerides (r = 0.25 and 0.36, respectively). Saturated fa t 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 li near regression models, abdomen-to-hip ratio was positively related to triglycerides and low density lipoprotein cholesterol (LDL-C) after a djusting for the effects of body mass index, alcohol intake, age, ciga rette smoking and physical activity level, but was not significantly r elated to HDL-C. When serum insulin level was included as a covariate, abdomen-to-hip ratio remained significantly related to LDL-C and trig lycerides, 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-hi p ratio and BMI. Further adjustment for saturated fat intake did not s ignificantly influence any of the relationships of abdomen-to-hip rati o or insulin level with the lipid variables. These cross-sectional dat a suggest that abdominal obesity is related to triglycerides and LDL-C , although part of the influence of abdominal obesity appears to be me diated by hyperinsulinemia. Saturated fat intake is associated with ab dominal obesity and hyperinsulinemia but does not appear to influence the relationships of obesity and hyperinsulinemia with lipids and lipo proteins.