The relationship of insulin sensitivity and metabolic clearance of insulin to adiposity and sex hormone binding globulin.

Previous studies have shown that sex hormone binding globulin (SHBG) is negatively associated with insulin concentrations in premenopausal women. We determined insulin sensitivity (SI) and clearance (KI) in 8 non-obese men and 13 nonobese premenopausal women using the minimal model of Bergman and colleagues. Insulin clearance and insulin sensitivity were strongly correlated (p less than 0.05). SHBG was positively correlated with SI (i.e., individuals with high levels of SHBG had greater insulin sensitivity) in both men (r = .738, p less than 0.05) and women (r = .577, p less than 0.06). Insulin clearance was also positively correlated with SHBG in men (r = .619) and in women (r = .476) (0.05 less than p less than 0.10). Since obese subjects have both lower SHBG concentrations and decreased insulin sensitivity, we examined the effect of correcting for adiposity by partial correlation analyses. SHBG was not associated with KI after adjustment for BMI. SHBG was still positively correlated with SI in both men (r = .708) (p less than 0.06) and women (r = 0.541) (p less than 0.06), suggesting that the relationship between SHBG and insulin sensitivity is not confounded by obesity. Thus, the relationship of androgenicity with insulin sensitivity (but not insulin clearance) was independent of adiposity.