Clinical manifestations and insulin resistance (IR) in polycystic ovary syndrome (PCOS) among South Asians and Caucasians: is there a difference?

Abstract

Polycystic ovary syndrome (PCOS) is more prevalent in South Asian women residing in the UK than in Caucasians. Insulin resistance (IR) is central to the pathogenesis of PCOS, while type 2 diabetes is commoner in South Asians. We aimed to determine a possible ethnic difference in the clinical and biochemical characteristics of South Asian vs. Caucasian women with PCOS. A case-control cross-sectional observational study of consecutive women with anovular PCOS (47 South Asians, 40 Caucasians) and their age-matched controls (11 South Asians and 22 Caucasians). Index subjects: a questionnaire-based interview on clinical symptoms and family history; anthropometric measurements, clinical observations of the presence and degree of acne, hirsutism and acanthosis nigricans; transvaginal pelvic ultrasound; biochemical analyses of fasting blood sugar, fasting plasma insulin, fasting lipids, testosterone, and SHBG concentrations. age- and weight-matched unrelated women from the same ethnic backgrounds without PCOS seeking treatment for male infertility were studied by similar methods to those used with the index subjects. South Asians with PCOS presented at a younger age (age 26 +/- 4 vs. 30.1 +/- 5 years, P = 0.005). Body mass index (BMI) and waist : hip ratios were similar in the two affected cohorts. More South Asians had oligomenorrhoea commencing at a younger age. Hirsutism (Ferriman Gallwey score 18 vs. 7.5, P = 0.0001), acne, acanthosis nigricans and secondary infertility were significantly more prevalent in South Asians. The fasting glucose was similar (4.52 +/- 0.08 vs. 4.62 +/- 0.09 mmol/l, P = 0.25), the fasting insulin higher (89.4 +/- 8.9 vs. 48.6 +/- 4.8 pmol/l, P = 0.0001) and insulin sensitivity (IS) lower (0.335 +/- 0.005 vs. 0.357 +/- 0.002, P = 0.0001) among South Asians. Serum SHBG was significantly less in South Asians (35 +/- 3.3 vs. 55 +/- 9.4 nmol/l, P = 0.02), while serum testosterone was similar (2.69 +/- 0.11 vs. 2.64 +/- 0.13 nmol/l, P = 0.37). We conclude that South Asians with anovular PCOS seek treatment at a younger age, have more severe symptoms, and have higher fasting insulin concentrations and lower insulin sensitivity than Caucasians.