Alterations of insulin sensitivity, clearance, and secretion, either alone or in combination, in women with PCOS: impact on metabolic profile and androgenemia

Abstract STUDY QUESTION What is the role of insulin resistance (IR), increased insulin secretion, and impaired insulin clearance, either alone or in combination, on metabolic features and androgen levels in women with PCOS? SUMMARY ANSWER IR, reduced insulin clearance and increased insulin secretion independently contribute to predicting hyperandrogenemia, whereas metabolic abnormalities may differ according to the mechanisms underlying hyperinsulinemia. WHAT IS KNOWN ALREADY Hyperinsulinemia is a common finding in women with PCOS, and it is closely associated with the metabolic and endocrine alterations of these women. It is considered a compensatory mechanism to IR, and results from two separate mechanisms: increased secretion and/or reduced insulin clearance. The contribution of these two distinct adaptive processes may differ, and the implications of these differences are poorly understood. STUDY DESIGN, SIZE, DURATION Cross-sectional study of 355 women with PCOS recruited in the Verona 3P study from 2010 to 2021. PARTICIPANTS/MATERIALS, SETTING, METHODS Women with PCOS, diagnosed by the Rotterdam criteria, underwent a hyperinsulinemic euglycemic clamp, to measure insulin sensitivity (M-clamp) and to calculate insulin clearance (MCRI). Insulin secretion was estimated by the HOMA β-index. Serum androgens were measured by LC/MS-MS and equilibrium dialysis. MAIN RESULTS AND THE ROLE OF CHANCE Hyperinsulinemia was found in 65.4% women with PCOS. Insulin sensitivity was impaired in 69.6% subjects, MCRI was reduced in 57.2%, and HOMA β-index was increased in 60.0% women. Overall, 311 subjects (87.6%) had at least one of these insulin metabolism alterations. The combination of the three alterations was found in 127 (35.8%) women, whereas 98 (27.6%) had two alterations: 30 had IR and reduced MCRI, 47 had IR and increased HOMA β-index, 21 had reduced MCRI and increased HOMA β-index. Eighty-six (24.2%) women had only one alteration: 43 had IR, 25 had reduced MCRI, 18 had increased HOMA β-index; finally, 44 (12.4%) subjects showed no alterations. Anthropometric parameters, and fasting glucose and insulin, were progressively lower in women with 3, 2, 1, or 0 insulin metabolism alterations. Similar trends were observed for serum triglycerides, blood pressure, and androgens, whereas progressively increasing values were observed for high-density lipoprotein-cholesterol and sex hormone-binding globulin. In logistic regression analysis, after adjusting for age and fat mass, IR and increased insulin secretion were independent predictors of altered glucose tolerance, whereas IR and low MCRI were independent predictors of metabolic syndrome; in multivariable analysis, M-clamp, MCRI, and HOMA β-index were all independent predictors of serum free testosterone. LIMITATIONS, REASONS FOR CAUTION Insulin secretion was estimated by a validated surrogate index, whose performance may be suboptimal. This study was carried out in Caucasian women. Therefore, our findings may not be generalizable to other ethnic groups. Finally, the cross-sectional design of the study limits the causal inference of the results. WIDER IMPLICATIONS OF THE FINDINGS The presence of IR, reduced MCRI, and increased insulin secretion, especially when combined, worsens metabolic outcomes and androgen levels in women with PCOS. However, these factors may play a different role in determining altered glucose metabolism or metabolic syndrome, whereas all of them independently contribute to hyperandrogenemia. STUDY FUNDING/COMPETING INTEREST(S) Academic grants to P. Moghetti from the University of Verona (FUR 2010-2022). All authors declare no conflict of interest. TRIAL REGISTRATION NUMBER N/A.