The prevalence of Type 2 diabetes is not increased in normal-weight women with PCOS

STUDY QUESTION: Is oral glucose tolerance test (OGTT) needed in all women with polycystic ovary syndrome (PCOS)?SUMMARY QNSWER: OGTT is not routinely needed in women with PCOS and BMI < 25 kg/m2.WHAT IS KNOWN ALREADY: PCOS is associated with insulin resistance and increased prevalence of prediabetes and Type 2 diabetes (T2D) which is closely linked to obesity and possibly age, ethnicity and PCOS phenotype. Several guidelines recommend OGTT upon diagnosis of PCOS and during follow-up.STUDY DESIGN, SIZE, DURATION: A Nordic cross-sectional study including 876 women.PARTICIPANTS/MATERIALS, SETTING, METHODS: The 876 Nordic women with PCOS, aged 14-57 years, were examined for T2D and prediabetes (impaired glucose tolerance [IGT] or impaired fasting glucose (IFG) by OGTT.MAIN RESULT AND THE ROLE OF CHANCE: Of all study subjects 3% (23/876) had T2D, 23% (204/876) prediabetes and 74% (649/876) had normal glucose tolerance (NGT). Increased BMI and waist circumference were significantly (P < 0.001) associated with prevalence of prediabetes and T2D. No normal-weight woman (BMI < 25 kg/m2) was diagnosed with T2D. The prevalence of BMI ≥ 25 kg/m2 was 66% (578/ 876). 91% of women (21/23) with T2D had BMI ≥ 30 kg/m2. Testosterone levels and PCOS phenotype did not predict 2-h glucose levels during OGTT after adjustment for BMI and age.LIMITATIONS, REASONS FOR CAUTION: The present study included cross-sectional data and prospective studies are needed to confirm our results. These results may not apply to populations of other ethnic origin.WIDER IMPLICATIONS OF THE FINDINGS: Routine OGTT may not be indicated in normal-weight women with PCOS.STUDY FUNDING/COMPETING INTEREST(S): None.TRIAL REGISTRATION NUMBER: N/A.