The relation between clinical manifestations of polycystic ovary syndrome and beta-cell function

Hyperandrogenism in patients with polycystic ovary syndrome has been shown to correlate with hyperinsulinaemia of insulin resistance. We have investigated if basal levels of insulin and the response to the intravenous administration of glucagon can reveal insulin resistance in patients with polycystic ovary syndrome.

Nine obese (BMI > 25 kg/m2) and nine non-obese (BMI 19-25 kg/m2) women with PCOS, chosen from a population of 91 women attending the infertility clinic, and 19 normally cycling women (seven obese, 12 non-obese) were studied. Oligo or amenorrhoea, hirsutism, and 12 or more follicles in a given ovary were selection criteria.

Glucagon, 1 mg, was given intravenously to 18 of the 91 women and to the control subjects. Blood was taken at -5, 0, 5, 10 and 15 minutes for measurements of integrated areas under the response curve for insulin, C-peptide and glucose, respectively. Basal blood samples were drawn for fasting insulin, C-peptide, glucose, testosterone, sex hormone-binding globulin (SHBG), free fatty acids and IGF-I measurements. The free androgen index was calculated according to the formula FAI = testosterone x 100/SHBG.

There were no significant differences in maximal increment and area under the response curve for glucose, C-peptide and insulin. FAI was significantly higher in all patients with features of polycystic ovary syndrome. However, fasting insulin levels were significantly higher only in obese patients when compared with obese control subjects and lean patients.

The administration of 1 mg glucagon i.v. did not distinguish patients with polycystic ovary syndrome from control subjects. The mild insulin resistance of polycystic ovary syndrome is related only to obesity and is therefore unlikely to play an important role in the hyperandrogenism associated with the syndrome.