Polycystic ovary syndrome (PCOS) is a very common endocrine disorder characterized by chronic anovulation, clinical and/or biochemical hyperandrogenism, and/or polycystic ovaries. But most experts consider that hyperandrogenism is the main characteristic of PCOS. Several theories propose different mechanisms to explain PCOS manifestations: (1) a primary enzymatic default in the ovarian and/or adrenal steroidogenesis; (2) an impairment in gonadotropin releasing hormone (GnRH) secretion that promotes luteal hormone (LH) secretion; or (3) alterations in insulin actions that lead to insulin resistance with compensatory hyperinsulinemia. However, in the past 20 years there has been growing evidence supporting that defects in insulin actions or in the insulin signalling pathways are central in the pathogenesis of the syndrome. Indeed, most women with PCOS are metabolically insulin resistant, in part due to genetic predisposition and in part secondary to obesity. But some women with typical PCOS do not display insulin resistance, which supports the hypothesis of a genetic predisposition specific to PCOS that would be revealed by the development of insulin resistance and compensatory hyperinsulinemia in most, but not all, women with PCOS. However, these hypotheses are not yet appropriately confirmed, and more research is still needed to unravel the true pathogenesis underlying this syndrome. The present review thus aims at discussing new concepts and findings regarding insulin actions in PCOS women and how it is related to hyperandrogenemia.

Objective To assess metabolic and endocrine defects in girls genetically predisposed to polycystic ovary syndrome (PCOS). Design Controlled cross-sectional study. Setting University hospital. Patients Nine girls aged 8–14 years having a first-degree relative diagnosed with PCOS (PCOSr) and 10 age-matched girls unrelated to PCOS. Intervention None. Main outcome measure Insulin sensitivity determined by frequently sampled intravenous glucose tolerance testing (ISFSivGTT) and insulin-induced non-esterified fatty acid suppression (NEFAsupp), estimated by the log-linear slope of NEFA levels during the first 20 min of FSivGTT. Results In comparison to controls, PCOSr had higher body mass index Z-score (BMI-z), waist circumference and waist/height ratio. Levels of the androgen 17α-hydroxyprogesterone (17OHPg) were significantly increased in PCOSr, independently of adiposity, and inversely correlated with ISFSivGTT. ISFSivGTT was decreased and NEFAsupp was less steep in PCOSr as compared to controls, independently of BMI-z and 17OHPg. NEFAsupp was more pronounced with increasing ISFSivGTT, independently of adiposity. Conclusions Girls at high risk of developing PCOS display increased adiposity and 17OHPg levels, but are mainly characterized by global insulin resistance and resistance to insulin-induced suppression of lipolysis that were independent of adiposity and 17OHPg levels. Therefore, genetic predisposition to PCOS may be related to early insulin resistance and adipocyte dysfunction.

BackgroundWe and others have observed that young girls predisposed to polycystic ovary syndrome (PCOS) display defective insulin sensitivity, beta-cell function and non-esterified fatty acids (NEFA) suppressibility during early pubertal years, compared to controls. Our objective is to assess whether these differences in glucose and NEFA metabolisms persist after 5 years in late/post-puberty.MethodsWe conducted a prospective cohort study between 2007 and 2015 with 4–6 years of follow-up in an academic institution research center. We compared 8 daughters and sisters of PCOS women (PCOSr) to 8 age-matched girls unrelated to PCOS (±1.5 years). Girls were assessed initially at 8–14 years old and re-assessed after a median follow-up of 5.4 years, at 13–21 years old. Our main measures were a frequently sampled intravenous glucose tolerance test (FSivGTT)-derived insulin sensitivity (IS) and beta-cell function (disposition index, DIFSivGTT); and indices of NEFA suppression during FSivGTT (logn-linear slope of NEFA and T50 of NEFA suppression).ResultsAt follow-up, both PCOSr and controls had similar results: IS = 3.2 vs 3.4 (p = 0.88), DIFSivGTT = 1926 vs 1380 (p = 0.44), logn-linear slope = −0.032 vs −0.032 (p = 0.88) and T50NEFA = 18.1 vs 20.8 min (p = 0.57). IS, DIFSivGTT and NEFA suppressibility were stable in PCOSr after 5 years, but decreased significantly in controls (all p < 0.05).ConclusionsImpaired metabolism observed during early puberty in girls predisposed to PCOS remains stable after 5 years whereas control girls deteriorated their metabolic parameters. Therefore, both groups become comparable in late/post-puberty. Early puberty may thus represent a window during which metabolic alterations are transiently apparent in girls at risk of PCOS.

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