Effect of the age at menarche and menopause status interaction on type 2 diabetes: the Henan Rural Cohort Study.

PURPOSE: The aims of this study were to evaluate the effect of age at menarche (AM) on type 2 diabetes mellitus (T2DM) and to assess whether the fasting plasma glucose (FPG) and homeostasis model assessment (HOMA) index responses to AM and menopause status interact in Chinese rural adults. METHODS: A cross-sectional, population-based study including 23 138 participants was performed. Logistic regression and multivariable linear regression were performed to investigate the relationship between AM and glucose status. Generalized linear model was used to calculate the interaction term of AM and menopause status on FPG and the HOMA index. Interaction plot was used to interpret the significant interaction effect. RESULTS: Women in the later menarche age group (>/=18 years) had a 17.7% lower risk of T2DM (95% confidence interval [CI]: 0.712-0.951, P = .008), after adjusting for multiple variables. Further adjustment for body mass index (BMI) completely attenuated this association (odds ratio = 0.884, 95% CI: 0.764-1.024, P = .099). A significant interaction effect of AM and menopause status on T2DM (P = .004) was observed. The adverse effects of menopausal status on FPG and HOMA-2 of insulin resistance decreased with increasing menarche age, and the age ranges were limited to <18 and 9 to 19 years, respectively. CONCLUSIONS: Later menarche was associated with a lower risk of T2DM, and the association appears to be mediated by BMI. More importantly, the adverse effect of menopause status on T2DM was decreased along with increasing menarche age.