Diabetes Type 2 in Women: The Impact of EndogenousOestrogen, A Population-Based Study With About 2 Decades of Follow-Up.

AIMS: The role of endogenous oestrogen exposure (EEE) in type 2 diabetes (T2D) remains understudied despite its potential importance. This study aimed to assess T2D incidence in women with different endogenous oestrogen durations. MATERIALS AND METHODS: At the initiation of the study, 6273 post-menarche women above 20 years were included. After applying the exclusion criteria, 3,411 women remained (2,754 premenopausal and 657 menopausal). Each woman's EEE was determined, and they were monitored for the incidence of T2D. Based on the EEE duration, hazard ratios (HRs) and 95% confidence intervals (CI) for the T2D event were reported using Cox proportional hazards regression models. RESULTS: The mean age and menarcheal age (standard deviation) of participants were 39.3(12.5) and 13.5(1.5) years, respectively. Finally, 30.9% (1053) of the women developed diabetes (819 (29.7%) premenopausal and 234 (35.6%) menopausal). The age and BMI-adjusted model's findings indicated that, overall, the EEE z-score was inversely associated with T2D incidence in postmenarcheal women [HR 0.91, 95% CI 0.85-0.97], meaning that the risk of T2D decreased by 9% for every 1-SD increase in the EEE z-score. Furthermore, after full adjustment for potential confounders, the association remained statistically significant (HR = 0.90, 95% CI: 0.84-0.96). CONCLUSIONS: The findings suggest that longer EEE duration may reduce the risk of T2D, emphasising the importance of reproductive history in health assessments.