Ryu KJ, Kim MS, Kim HK, et al. - In this longitudinal case-control study, researchers intended to determine if there is an association between polycystic ovary syndrome (PCOS) and type 2 diabetes mellitus (T2DM) in Korean women. Patients with PCOS aged 15 to 44 years (n = 1,136) and control individuals (n = 5,675), matched 1:5 by age group, income, and region of residence. Data reported that15.7% and 14.4%, respectively, were obese (BMI ≥ 25 kg/m²) in the PCOS and control groups. In the PCOS and control groups, the incidence rate of T2DM was 15.84/1,000 and 5.80/1,000 person-years, respectively. In both obese and nonobese women, PCOS is independently associated with an increased incidence of T2DM. For both obese and nonobese women with PCOS in Korea, screening for T2DM should be considered.