Objective: To assess the differential impact of obesity and hyperinsulinaemia on cardiovascular risk factors in non-diabetic, normotensive subjects.
Design: Cross-sectional (n = 1897) and 8-year follow-up data (n = 1047) from non-diabetic, normotensive, normolipidaemic men and women (screened in the San Antonio Heart Study) with a body mass index [BMI] in the range 15.2-58.5 kg/m2.
Results: 183 of 849 obese subjects (BMI > or = 27 kg/m2 in men, > or = 26 in women) had fasting and post-glucose plasma insulin concentrations superimposable on those of the normoinsulinaemic segment of the non-obese subgroup. Yet, waist/hip ratio (WHR), systolic and diastolic blood pressure, fasting plasma glucose and triglyceride levels were significantly higher, and serum HDL-cholesterol concentrations lower, in the obese than in the non-obese. In the whole sample (n = 1897), both obesity and hyperinsulinaemia were independently associated with higher WHR, arterial blood pressure, fasting and post-load plasma glucose and triglyceride concentrations, and lower HDL-cholesterol levels. This pattern of associations was essentially unaltered after adjustment by WHR. In the subjects re-tested 8 years following the initial screening, the 8-year changes in the level of cardiovascular risk factors were significantly associated with the corresponding changes in both fasting plasma insulin and BMI, independently of one another.
Conclusions: Although plasma insulin and body weight are closely inter-related variables, they have a separate impact on the cardiovascular risk profile in normal subjects.