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.

No abstract

OBJECTIVETo characterize physiologic subtypes of gestational diabetes mellitus (GDM).RESEARCH DESIGN AND METHODSInsulin sensitivity and secretion were estimated in 809 women at 24–30 weeks' gestation, using oral glucose tolerance test–based indices. In women with GDM (8.3%), defects in insulin sensitivity or secretion were defined below the 25th percentile in women with normal glucose tolerance (NGT). GDM subtypes were defined based on the defect(s) present.RESULTSRelative to women with NGT, women with predominant insulin sensitivity defects (51% of GDM) had higher BMI and fasting glucose, larger infants (birth weight z score 0.57 [−0.01 to 1.37] vs. 0.03 [−0.53 to 0.52], P = 0.001), and greater risk of GDM-associated adverse outcomes (57.6 vs. 28.2%, P = 0.003); differences were independent of BMI. Women with predominant insulin secretion defects (30% of GDM) had BMI, fasting glucose, infant birth weights, and risk of adverse outcomes similar to those in women with NGT.CONCLUSIONSHeterogeneity of physiologic processes underlying hyperglycemia exists among women with GDM. GDM with impaired insulin sensitivity confers a greater risk of adverse outcomes.

The progressive increase of insulin resistance observed in pregnancy contributes to the pathophysiology of gestational diabetes mellitus (GDM). There is controversy whether vitamin D deficiency contributes to abnormal glycemic regulation in pregnancy. We tested the associations between first trimester 25-hydroxyvitamin D (25OHD) levels and: 1) the risk of developing GDM; 2) insulin resistance/sensitivity, beta cell function and compensation indices in a large population-based prospective cohort of pregnant women. Participants (n = 655) were seen at first (6-13 weeks) and second (24-28 weeks) trimesters for blood samples. At first trimester, 25OHD levels were measured. At second trimester, glucose and insulin were measured 3 times during the oral glucose tolerance test to estimate insulin resistance (HOMA-IR), beta cell function (HOMA-B), insulin sensitivity (Matsuda index), insulin secretion (AUCins/gluc) and beta cell compensation (ISSI-2). Based on IADPSG criteria, 54 participants (8.2 %) developed GDM. Lower first trimester 25OHD levels were associated with higher risk of developing GDM even after adjustment for vitamin D confounding factors and GDM risk factors (OR = 1.48 per decrease of one SD in 25OHD levels; P = 0.04). Lower first trimester 25OHD levels were associated with higher HOMA-IR (r = - 0.08; P = 0.03), lower Matsuda index (r = 0.13; P = 0.001) and lower ISSI-2 (r = 0.08; P = 0.04). After adjustment for confounders, we found no significant association with HOMA-B and AUCins/gluc. Our results suggest that low levels of 25OHD at first trimester are (1) an independent risk factor for developing GDM and (2) associated with insulin resistance at second trimester.

OBJECTIVETo evaluate the associations between adiponectin levels and 1) the risk of developing gestational diabetes mellitus (GDM), and 2) insulin resistance/sensitivity, β-cell function, and compensation indices in a prospective cohort representative of the general population of pregnant women.RESEARCH DESIGN AND METHODSWe performed anthropometric measurements and collected blood samples at 1st (6–13 weeks) and 2nd (24–28 weeks) trimesters. Diagnosis of GDM was made at 2nd trimester based on a 75-g oral glucose tolerance test (International Association of the Diabetes and Pregnancy Study Groups criteria). Insulin was measured (ELISA; Luminex) to estimate homeostasis model assessment of insulin resistance (HOMA-IR), β-cell function (HOMA-B), insulin sensitivity (Matsuda index), insulin secretion (AUCinsulin/glucose), and β-cell compensation (insulin secretion sensitivity index-2). Adiponectin was measured by radioimmunoassay.RESULTSAmong the 445 participants included in this study, 38 women developed GDM. Women who developed GDM had lower 1st-trimester adiponectin levels (9.67 ± 3.84 vs. 11.92 ± 4.59 µg/mL in women with normal glucose tolerance). Lower adiponectin levels were associated with higher risk of developing GDM (OR, 1.12 per 1 µg/mL decrease of adiponectin levels; P = 0.02, adjusted for BMI and HbA1c at 1st trimester). Adiponectin levels at 1st and 2nd trimesters were associated with HOMA-IR (both: r = −0.22, P < 0.0001) and Matsuda index (r = 0.28, P < 0.0001, and r = 0.29, P < 0.0001). After adjustment for confounding factors, we found no significant association with HOMA-B and AUCinsulin/glucose.CONCLUSIONSPregnant women with lower adiponectin levels at 1st trimester have higher levels of insulin resistance and are more likely to develop GDM independently of adiposity or glycemic measurements.

Epidemiological studies have produced evidence that unfavorable intrauterine environments during fetal life may lead to adverse outcomes in adulthood. We have previously shown that a low-sodium diet, given to pregnant rats over the last week of gestation, results in intrauterine growth restriction (IUGR). We hypothesize that pups born with IUGR are more susceptible to the development of hypertension in adulthood. IUGR fetuses and rats aged 1 wk were characterized for organ growth and renal morphogenesis. The adults (12 wk) were evaluated for weight, systolic blood pressure, activity of the renin-angiotensin-aldosterone system (RAAS), and renal function; hearts and kidneys underwent a histological examination. Brain and cardiac ventricle-to-body ratios were increased in IUGR fetuses compared with age-matched controls, whereas the kidney-to-body ratio was unchanged. Systolic blood pressure was elevated in both IUGR male and female adults. Plasma aldosterone levels were not correlated with increased plasma renin activity. Moreover, urinary sodium was decreased, whereas plasma urea was elevated in both males and females, and creatinine levels were augmented only in females, suggesting a glomerular filtration impairment in IUGR. In our model of IUGR induced by a low-sodium diet given to pregnant rats, high blood pressure, alteration of the RAAS, and renal dysfunction are observed in adult life. Differences observed between male and female adults suggest the importance of gender in outcomes in adulthood after IUGR.

No abstract

No abstract