title: Menarchal timing in type 1 diabetes through the last 4 decades.
abstract: OBJECTIVE
  We sought to examine whether age at menarche has changed over the past 4 decades by comparing age at menarche by year of diagnosis with type 1 diabetes.
  
  
  METHODS
  This work consisted of a cross-sectional study of age at menarche in two cohorts: adolescents (ages 11-24 years, n = 228) and adults (ages 19-55 years, n = 290, enrolled in the Coronary Artery Calcification in Type 1 Diabetes study).
  
  
  RESULTS
  The adolescent cohort reported a younger age of menarche than the adult women with type 1 diabetes (12.69 ± 0.08 vs. 13.22 ± 0.12 years, mean ± SE, P < 0.001). Age at menarche was later in both adolescent girls and adult women with type 1 diabetes diagnosed before menarche (12.82 ± 1.16 and 13.7 ± 2.23 years) than for individuals diagnosed after menarche (12.12 ± 1.25 and 12.65 ± 1.38 years, P < 0.001 for both). Age at menarche was then examined by decade of type 1 diabetes diagnosis (1970-1979, 1980-1989, 1990-1999, and 2000-2009). Age at menarche significantly declined over the 4 decades (P = 0.0002). However, the delay in menarche among girls diagnosed with type 1 diabetes before menarche compared with those diagnosed after menarche was also significant across all decades (P < 0.0001) and did not change significantly over time (P = 0.41 for interaction of cohort and diagnosis premenarche).
  
  
  CONCLUSIONS
  Age at menarche has declined over the past 4 decades among girls with type 1 diabetes, but a delay in age at menarche remains among individuals diagnosed before menarche compared with individuals diagnosed after menarche.
authors.affiliation: Barbara Davis Center for Childhood Diabetes, University of Colorado Denver, CO, USA.
authors.forename: Bahareh
authors.initials: B
authors.lastname: Schweiger
authors.forename: Georgeanna J
authors.initials: GJ
authors.lastname: Klingensmith
authors.forename: Janet K
authors.initials: JK
authors.lastname: Snell-Bergeon
mesh_terms: D000293:Adolescent; D000328:Adult; D002648:Child; D003430:Cross-Sectional Studies; D003922:Diabetes Mellitus, Type 1 / Q000503:physiopathology*; D005260:Female; D006801:Humans; D008572:Menarche; D008875:Middle Aged; D055815:Young Adult