Serum androgens in hyperinsulinemic Pima Indian and obese Caucasian women and their response to short-term insulin infusion.

Insulin resistance and its attendant hyperinsulinemia has been linked with hyperandrogenism. Insulin resistance is characteristic of the Pima Indians of the Gila River Indian community in central Arizona. Serum androgens, testosterone and dehydroepiandrosterone sulfate (DHEA-S) were quantitated at baseline and in response to low- and high-dose insulin infusion in 11 obese, hyperinsulinemic Pima Indian and 10 obese, hyperinsulinemic Caucasian women and were compared with baseline androgens in 16 nonobese Caucasian women. While there was no significant testosterone or DHEA-S response to short-term insulin infusion in either Pimas or obese Caucasians, both these groups had higher baseline testosterone concentrations (67 +/- 6.5 ng/dl in the Pimas, 55 +/- 5.9 ng/dl in the obese Caucasians) as compared with the nonobese Caucasians (28 +/- 2 ng/dl; p < 0.001). Baseline DHEA-S concentrations were not significantly different in the three groups. Given the hyperinsulinemic status of both the Pimas and the obese Caucasians, the finding of higher testosterone concentrations in these subjects as compared with nonobese Caucasians supports a role for insulin in ovarian androgen production and demonstrates that hormonal interactions that may be operating in obese hyperinsulinemic Caucasian subjects also operate in obese, hyperinsulinemic Pima Indians.