Objective— To examine if the risk for CHD increases progressively with increases in the BMI of normoglycemic, hyperinsulinemic, morbidly obese women (BMI ≥ 35 kg/m2).
Research Design and Methods— Insulin sensitivity was evaluated by calculating an ISI following an OGTT. There was a significant linear relationship between ISI and BMI fitted by two straight lines intersecting at a point corresponding to a BMI of 29.7 ± 1.5 kg/m2. Significant linear relationships between insulin sensitivity and BMI were obtained below and above this breakpoint. Similarly, a breakpoint for the relation between dBP and BMI corresponding to a BMI ≥ 33.7 ± 3.4 kg/m2 was obtained. Significant linear relationships between BMI and plasma fasting glucose, triglyceride, cholesterol, HDL cholesterol, sBP, or dBP were not observed in the women with a BMI > 35 kg/m2.
Results— Compared with lean (BMI <27) women of similar age, the morbidly obese patients appear to be at a higher risk for CHD. This is suggested by statistically significant increases in fasting insulin (mean ± SD; 187 ± 137 vs. 64.2 ± 16.2 pM) and triglyceride levels (128 ± 78.1 vs. 73 ± 25 mg/dl), sBP (132 ± 114 vs. 104 ± 15.8) and dBP (84 ± 72 vs. 67 ± 2.1 mmHg), and decreases in HDL cholesterol (1.03 ± 0.44 vs. 1.29 ± 0.82 mM) and apo A-I (91 ± 55 vs. 122 ± 35 mg/dl) concentrations.
Conclusions— It appears that there may be a threshold of body mass up to which insulin sensitivity is associated with CHD risk. Above this threshold, there does not appear to be a progressive increase in the risk factors for CHD with increases in BMI.
