Is leptin concentration associated with the insulin resistance syndrome in nondiabetic men?

Objective: Insulin resistance has been strongly associated with cardiovascular risk. Recently, leptin, a hormone that regulates appetite, has been associated with both obesity and insulin resistance. However, the possible relation of leptin to the insulin resistance syndrome has been controversial. Research Methods and Procedures: To explore this issue, we examined the relation of leptin to blood pressure, lipid levels, low density lipoprotein (LDL) size, and glucose levels in 87 normoglycemic men. Results: Leptin levels were significantly correlated with body mass index (BMI) (r = 0.494), fasting insulin (r = 0.576), whole-body glucose disposal rate (GDR) (r=-0.566), fasting glucose (r=0.510), total triglycerides (r = 0.294), apolipoprotein B (r = 0.223), systolic blood pressure (r=0.223), and LDL size (r=-0.244). After adjustment for BMI and GDR, leptin levels remained significantly correlated with fasting insulin, fasting glucose, triglyceride, apolipoprotein B, and systolic blood pressure. Leptin levels were also correlated with the number of metabolic risk factors (dyslipidemia, systolic blood pressure, and fasting glucose). Discussion: We conclude that leptin concentrations may be associated with several cardiovascular risk factors related to insulin resistance syndrome. These associations are only partly explained by leptin's relationship with BMI and GDR.