Acute insulin response to intravenous glucagon in polycystic ovary syndrome

In order to evaluate the acute insulin response after i.v. injection of glucagon in polycystic ovary syndrome (PCOS), 35 women affected by PCOS and 11 normo-ovulatory controls underwent a 75 g oral glucose tolerance test (OGTT) and, 2 days later, a glucagon test (1 mg i.v.). Patients were analysed according to their degree of obesity; the insulin release after glucagon injection for lean PCOS subjects and control women was not statistically significantly different. Conversely obese PCOS patients had higher insulin secretion after both i.v. glucagon and OGTT when compared to the other groups. Moreover the insulin secretory patterns were heterogeneously represented in lean and obese PCOS women. When the patients were analysed according to their insulinaemic response to OGTT, normo-insulinaemic PCOS women and control subjects had a similar insulin response to i.v. glucagon whereas the hyper-insulinaemic PCOS group had a higher insulin response (P < 0.0001). Moreover, a highly significant relationship was found between the insulin response to OGTT and to glucagon administration in the PCOS population (P < 0.0001; r = 0.73), which was maintained also after controlling for obesity. Our results are consistent with the hypothesis that PCOS patients could have an insulin hyper-response to glucagon administration, that is partially independent from obesity and related to their insulinaemic status. Moreover, the glucagon test could represent an effective alternative to OGTT in screening insulin disorders of PCOS patients (at least in the absence of other risk factors), due to its reliability, simplicity, and speed of performance.