Background
Age at menarche, a reproductive marker, is associated with risk of type 2 diabetes in later life. The aim of this study was to investigate the association between other female reproductive markers and the risk of incident diabetes, and to examine whether any associations can be explained by excess body weight in midlife.
Methods
We pooled individual-level data from 126,721 mid-aged women from eight cohort studies participating in the International Collaboration for a Life Course Approach to Reproductive Health and Chronic Disease Events (InterLACE) consortium. We used generalised linear mixed models to quantify the associations between age at menarche, age at first birth, parity, menopausal status, and incident diabetes. We stratified by body mass index (BMI) when there was an evidence of an interaction with BMI.
Results
Over a median follow-up of 9 years, 4,073 cases of diabetes were reported. Women with menarche by age 10 years were at higher risk of incident diabetes after adjusting for BMI (RR 1.18, 95%CI 1.02-1.37), compared with those with menarche at 13 years; however, the increased risk was only apparent among women with a BMI ≥25 kg/m2. A U-shaped relationship was observed between parity and risk of diabetes. Women with a hysterectomy/oophorectomy had an increased risk of diabetes (RR 1.17, 95%CI 1.07-1.29), compared with pre-/peri-menopausal women.
Conclusion
Several markers of a woman's reproductive history appear to be modestly associated with incident diabetes in later life. Maintaining a normal weight in adult life may ameliorate any increase in risk conferred by early menarche.