Thong EP, Milat F, Joham AE, et al. - Researchers conducted this population‐based study to assess changes in body mass index (BMI) and the association between obesity, menstrual irregularity, and polycystic ovary syndrome (PCOS) in young women with T1D relative to controls. A longitudinal observational study utilizing data from the Australian Longitudinal Study in Women’s Health of the cohort born in 1989–95, from 2013–2015. Overall, 15,926 women were involved at baseline (T1D, n = 115; controls, n = 15,811). At Year 2, 61 women with T1D and 8,332 controls remained. Compared with those with normal BMI, obesity conferred a 4‐fold increased risk of PCOS. According to findings,  obesity is prevalent among women with T1D and may be a major contributor to the higher risk of menstrual irregularity and PCOS in this cohort, which represents an important opportunity for prevention and intervention.