There is controversy surrounding the impact of obesity on the development of type 2 diabetes mellitus (T2DM) among women with polycystic ovary syndrome (PCOS). We aimed to clarify the role of PCOS per se in the development of T2DM by identifying the population-based incidence rate of T2DM among women with PCOS according to risk factors including body-mass index (BMI), ethnicity, and family history of T2DM.
We undertook a historical population-based cohort study of women aged 18-23 years followed-up over 15 years (between years 2000 and 2015) using the Australian Longitudinal Study on Women’s Health (ALSWH) database. The study cohort consisted of women with self-reported PCOS and women without a diagnosis of PCOS (controls). We undertook survival analysis to identify potential predictors of T2DM using Cox Proportional Hazard Model and person-time analysis to calculate incidence rates of T2DM per 1000 person-years (PY).
During a follow-up of 1,919 years of person-time, 186 women developed T2DM. The incidence rate of T2DM was 4.22 per1000 (PY) in PCOS vs. 1.02 per 1000 PY in controls (p<0.001). The Kaplan-Meier survival probability estimates at 15 years were: 0.952 and 0.988 for women with and without PCOS respectively. On sub-group analyses, BMI categories across lean, overweight, and obese women with PCOS [IRR (incidence rate ratio): 4.68, 3.52 and 2.36)respectively] showed a higher risk for T2DM compared to controls. In the multivariate Cox analysis, PCOS, BMI, education, and family history of T2DM all independently increased the risk for T2DM in all women. PCOS was the strongest predictor [HR: 3.38 (95% CI: 2.21, 5.18), p<0.001] adjusting for BMI, education, and family history of T2DM.
PCOS is independently associated with an increased incidence of T2DM among young adult women and this increased risk varies by BMI. Screening of young women for T2DM should be considered, based on their overall diabetes risk taking into account PCOS status, BMI, and other risk factors.
N. Kakoly: None. A. Earnest: None. H. Teede: None. L. Moran: None. D. Loxton: None. A.E. Joham: None.