Earlier Menarche Is Associated with Lower Insulin Sensitivity and Increased Adiposity in Young Adult Women

Objective We aimed to assess whether age at menarche was associated with insulin sensitivity in young adult women. Methods We studied 54 healthy young women aged 20–30 years. Participants were grouped according to age at menarche: Early (≤11.0 years; n=13), Average (>12.0 and ≤13.0 years; n=28), and Late (≥14.0 years, n=13). Primary outcome was insulin sensitivity measured using intravenous glucose tolerance tests and Bergman’s minimal model. Body composition was assessed using whole-body dual-energy X-ray absorptiometry. Results Earlier menarche was associated with lower insulin sensitivity (p=0.015). There was also a continuous increase in adiposity with younger age at menarche, which was associated with increased weight (p=0.001), BMI (p=0.002), total body fat (p=0.049), and truncal fat (p=0.020). Stratified analyses showed that insulin sensitivity in Early women (5.5 x10 -4 ·min -1 (mU/l)) was lower than in Average (8.0 x10 -4 ·min -1 (mU/l), p=0.021) and Late (8.6 x10 -4 ·min -1 (mU/l), p=0.033) groups. Early women (weight=66.1 kg; BMI=24.1 kg/m 2 ) were considerably heavier and fatter than Average (59.0 kg, p=0.004; 21.4 kg/m 2 , p=0.002) and Late (57.0 kg, p=0.001; 20.8 kg/m 2 , p=0.0009) women. Conclusions Early menarche is associated with lower insulin sensitivity and increased adiposity in young adulthood, potentially increasing the risk of type 2 diabetes and the metabolic syndrome later in life.