Body mass index (BMI) partially mediates the relationship between early menarche and increased risk for type 2 diabetes (T2D), according to study results published in Menopause.

Early menarche has been associated with a greater risk for diabetes and cardiovascular disease, but data have been conflicting for how BMI may mediate this relationship. Researchers in this study used data from 15,346 postmenopausal women from the Henan Rural Cohort Study in China to examine the association between age at first menstruation and T2D risk and to determine to what extent this relationship can be attributed to adiposity in a rural Chinese population.

Information about menarche was self-reported by women in questionnaires, and blood samples were tested for glucose levels after an overnight fast. Age at menarche was divided into 5 categories: ≤14 (early menarche), 15, 16 to 17 (reference), 18, and ≥19 years (late menarche).

Overall, mean age at recruitment was 61.5±7.7 years, mean age at menarche was 16.1±2.2 years, and prevalence of T2D was 12.6%. Women who reported early menarche (n=3660) were younger at study enrollment, were multiparous, consumed higher-fat diets, and were more likely to be overweight compared with the reference group (n=4865).

Each year of delay in age at menarche was associated with a 6% lower risk for T2D (odds ratio [OR], 0.94; 95% CI, 0.92-0.96; P <.001). After adjusting for multiple variables, women with early menarche were at a significantly higher risk of developing T2D (OR, 1.21; 95% CI, 1.06-1.38; P =.004), whereas those with late menarche had lower T2D risk (OR, 0.78; 95% CI, 0.66-0.92; P =.003).

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In a mediation analysis, the OR for T2D with age at menarche indicated both an indirect effect mediated by BMI and the direct effect of menarche age. The proportion of the effect from BMI on this association was 28%, according to the analysis.

Limitations to this study included a potential underestimation of diabetes prevalence, given that researchers did not use an oral glucose tolerance test to define diabetes. In addition, early-life BMI was not measured, which may have been a confounding factor.

With regard to future directions for this research, Stephanie S. Faubion, MD, MBA, medical director of the North American Menopause Society, told Endocrinology Advisor, “Being overweight remains the main risk factor for type 2 diabetes and is modifiable. Clinicians should continue to focus efforts on counseling their overweight and obese patients and providing resources for weight management.”

“Additional research (which includes ethnic/racial diverse populations) into reproductive factors such as age at menarche, parity, age at menopause, and history of hysterectomy/oophorectomy that may influence diabetes risk is important and may provide further insight into potential sex-based differences in risk for diabetes,” Dr Faubion added.

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Reference

Zhang L, Li Y, Wang C, et al. Early menarche is associated with an increased risk of type 2 diabetes in rural Chinese women and is partially mediated by BMI: the Henan Rural Cohort Study. Menopause. 2019;26(11).