Glucose tolerance and hyperinsulinaemia in obese women: role of adipose tissue distribution, muscle fibre characteristics and androgens

Abstract

The separate independent statistical contribution of abdominal distribution of fat, hyperandrogenicity and muscle morphology to glucose intolerance and hyperinsulinemia was analyzed in 88 obese women. In univariate analysis the waist/hip cicumference ratio (WHR), body fat and lean body mass were all positively associated, and SHBG levels were negatively associated with insulin and glucose values. Muscle fiber areas were positively correlated with insulin but not with glucose concentrations. Adjustment for other variables did not remove the positive association between WHR and fasting insulin and glucose concentrations. SHBG, free testosterone and type IIb fiber areas were, however, significant confounding factors in the relationship between WHR and summed insulin and glucose concentrations. We conclude that fat distribution in obese women is associated with fasting hyperglycemia and hyperinsulinemia, independently of androgens and muscle fiber morphology, but that reduced SHBG concentrations and increased type IIb fiber areas may partly explain increased glucose and insulin responses to an oral glucose load in abdominally obese women.