Insulin resistance but not impaired β-cell function: a key feature in Chinese normal-weight PCOS women with normal glucose regulation

Abstract

Objective: To evaluate insulin sensitivity and β-cell function in Chinese polycystic ovary syndrome (PCOS) women while taking into account the confounding variables including body mass index (BMI), blood glucose levels, ethnicity, medication history and a family history of type 2 diabetes. Study design: Cross-sectional analysis. Setting: Clinical research center in China.Subjects: 76 PCOS women and 20 age-matched healthy control women. Intervention: No. Main outcome measures: All subjects underwent botnia euglycemic-hyperinsulinemic clamp to assess their insulin sensitivity expressed as M value and β-cell function expressed as deposition index (DI). Results: Compared with age-matched controls, both DI and M (p < 0.05, respectively) value were lower in PCOS group with normal glucose regulation (NGR), and they (p < 0.05, respectively) were the lowest in PCOS group with impaired glucose regulation (IGR). The subgroup analysis showed that compared with normal-weight controls, DI (p = 0.072) was similar but M value (p < 0.05) was lower in normal-weight PCOS group with NGR, and DI (p < 0.05) and M value (p < 0.05) were lower in overweight PCOS group with NGR. DI and M value (p < 0.05, respectively) of overweight PCOS group with IGR were the lowest among all groups. Conclusions: There was insulin resistance but not impaired β-cell function in Chinese normal-weight PCOS women with NGR. Insulin resistance may be an intrinsic factor prior to impaired β-cell function of PCOS.