Association of age at menopause with type 2 diabetes mellitus in postmenopausal women in the United States: National Health and Nutrition Examination Survey 2011–2018

Introduction
The present study aimed to examine the impact of age at menopause on the type 2 diabetes mellitus (T2DM) risk in postmenopausal women.

Material and methods
We included 4,968 postmenopausal women from the National Health and Nutrition Examination Survey 2011–2018. Age at menopause was measured by single year and categorically (< 40 years, 40–44 years, 45–54 years, 55 years and above). The outcome variable T2DM was measured with self-report and fasting blood glucose level. We performed logistic regression to estimate the odds ratio (OR) (95% confidence interval [CI]). Linear regression was used to examine the correlation between age at menopause and age at T2DM.

Results
Of the 4,968 postmenopausal women, 796 (16.0%) had T2DM after menopause. The mean age at menopause was 44.2 years. The mean age at T2DM was 57.2 years. Adjusting for potential confounders, the ORs for the association between age at menopause of < 40 years, 40–44 years and ≥ 55 years and T2DM were 1.97 (95% CI: 1.47–2.63), 1.27 (95% CI: 0.90–1.79) and 0.98 (95% CI: 0.66–1.45), respectively, compared to women having menopause at age 45 to 54 years. Each increase by 1 year in age at menopause was associated with a 3% reduction in the prevalence of T2DM (95% CI: 2–5). Age at menopause was significantly correlated with age at T2DM. Each 1-year increase in age at menopause might lead to a decrease of 0.39 years in age at T2DM.

Conclusions
Premature menopause was associated with increased T2DM risk in women. The earlier menopause occurs, the younger is the age at which T2DM may occur.