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/m2) were considerably heavier and fatter than Average (59.0 kg, p=0.004; 21.4 kg/m2, p=0.002) and Late (57.0 kg, p=0.001; 20.8 kg/m2, 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.