Onset of the climacteric phase by the mid-forties associated with impaired insulin sensitivity:a birth cohort study

Objective: To investigate whether the early-onset menopausal transition is associated with deteriorated glucose tolerance in women in their mid-forties. Methods: A cross-sectional analysis of a cohort study including 2,632 women of the Northern Finland Birth Cohort 1966. The participants were divided into two groups by their menstrual history and follicle-stimulating hormone values at age 46: climacteric and preclimacteric women. Glucose and insulin parameters, as well as mathematical indices derived from them to evaluate insulin sensitivity, were compared between the groups. The results were adjusted for measured body mass index and smoking. The possible effect of hormone therapy was investigated in subanalyses excluding hormone therapy users. Results: Climacteric women (n = 379) were more often current smokers at age 46 (P = 0.008), and their body mass indices increased more from 31 to 46 years (P = 0.013), compared to preclimacteric women (n = 2,253). In a multivariable generalized linear model, being climacteric at age 46 was associated with several findings suggesting decreased insulin sensitivity: increased glycated hemoglobin (P < 0.001), 2-hour oral glucose tolerance test 30- and 60-minute insulin (P = 0.040 and 0.006, respectively), and area under the insulin curve (P = 0.005). Being climacteric also was associated with a decreased the McAuley (P = 0.024) and Belfiore indices (P = 0.027) and glucose tolerance test 60-minute glucose (P = 0.015). In subanalyses excluding hormone therapy users (n = 94), the results did not change significantly. Conclusions: Earlier onset of climacteric transition is associated with impaired insulin sensitivity in middle-aged women.