Does early menarche increase risk of type 2 diabetes?

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An epidemiologic study by Chinese investigators shows that age at menarche impacts risk of type 2 diabetes mellitus (T2DM) and the risk may be mediated by body mass index (BMI). The findings were published in Menopause.

The study enrolled more than 15,000 postmenopausal rural Chinese women, who provided their age at menopause and a blood sample for glucose testing. T2DM was defined as fasting plasma glucose ≥ 7.0 mmol/L or a self-reported history of diabetes and/or current use of insulin or oral hypoglycemia drugs after excluding type 1 diabetes mellitus or diabetes due to other causes. Age at menarche was given in five categories: ≤ 14, 15, 16, 17, 18, and ≥ 19 years. Overall, 12.6% of the participants were found to have T2DM and the mean age at menarche was 16.1±2.2 years.

The investigators assessed the relationship between age at menarche and T2DM using logistic regression and restricted cubic spline analysis. Covariates considered included demographic characteristics, lifestyle factors, and family history of diabetes and reproductive factors.

Risk of T2DM was 6% lower for each year that menarche was delayed (OR = 0.94; 95% CI = 0.92-0.96; P < 0.001). After adjustment for multiple variables, risk was higher in women who experienced menarche at age 14 or younger versus age 16 to 17 (Or = 1.21; 95% CI = 1.06-1.38; P = 0.004). Later menarche-defined as age 19 or older-was associated with a 22% lower risk of T2DM (OR = 0.78; 95% CI = 0.66-0.92; P = 0.03).

The authors said that after adjustment for demographics, lifestyle, family history of diabetes, and reproductive factors, the relationship between age at menarche and T2DM remained robust. Risk of T2DM was 21% higher for women with menarche at age 14 or younger than those who experienced it at age 16 to 17 years.

Looking at adult BMI using a mediating effect analysis, the investigators said that it partially mediated the association between age at menarche and T2DM and the proportion was 28%.

The authors said theirs was the first study to explore the relationship between T2DM and age at menarche in a rural Chinese population. They noted that the mean age of these women at menarche is later than in participants in other studies and ascribed the difference to poor nutrition in early life. “Determining a history of early menarche, “ the investigators concluded, “may help to identify women with an increased risk of T2DM.”