title: Long or highly irregular menstrual cycles as a marker for risk of type 2 diabetes mellitus.
abstract: BACKGROUND
  Although oligomenorrhea has been associated cross-sectionally with insulin resistance and glucose intolerance, it is not known whether oligomenorrhea is a marker for increased future risk of type 2 diabetes mellitus (DM).
  
  
  OBJECTIVE
  To prospectively assess risk of type 2 DM in women with a history of long or highly irregular menstrual cycles.
  
  
  METHODS
  The Nurses' Health Study II, a prospective observational cohort study.
  
  
  METHODS
  A total of 101 073 women who had no prior history of DM and who reported their usual menstrual cycle pattern at age 18 to 22 years on the baseline (1989) questionnaire.
  
  
  METHODS
  Incident reports of DM, with follow-up through 1997, compared among women categorized by menstrual cycle length (5 categories).
  
  
  RESULTS
  During 564 333 person-years of follow-up, there were 507 cases of type 2 DM. Compared with women with a usual cycle length of 26 to 31 days (referent category) at age 18 to 22 years, the relative risk (RR) of type 2 DM among women with a menstrual cycle length that was 40 days or more or was too irregular to estimate was 2.08 (95% confidence interval [CI], 1.62-2.66), adjusting for body mass index at age 18 years and several other potential confounding variables. The RR of type 2 DM associated with long or highly irregular menstrual cycles was greater in obese women, but was also increased in nonobese women (at body mass indexes at age 18 years of <25, 25-29, and >/=30 kg/m, RRs were 1.67 [95% CI, 1.14-2.45], 1.74 [95% CI, 1.07-2.82], and 3.86 [95% CI, 2.33-6.38], respectively).
  
  
  CONCLUSIONS
  Women with long or highly irregular menstrual cycles have a significantly increased risk for developing type 2 DM that is not completely explained by obesity.
authors.affiliation: Division of Women's Health, Brigham and Women's Hospital, 75 Francis St, Boston, MA 02115, USA. cgsolomon@bics.bwh.harvard.edu
authors.forename: C G
authors.initials: CG
authors.lastname: Solomon
authors.forename: F B
authors.initials: FB
authors.lastname: Hu
authors.forename: A
authors.initials: A
authors.lastname: Dunaif
authors.forename: J
authors.initials: J
authors.lastname: Rich-Edwards
authors.forename: W C
authors.initials: WC
authors.lastname: Willett
authors.forename: D J
authors.initials: DJ
authors.lastname: Hunter
authors.forename: G A
authors.initials: GA
authors.lastname: Colditz
authors.forename: F E
authors.initials: FE
authors.lastname: Speizer
authors.forename: J E
authors.initials: JE
authors.lastname: Manson
mesh_terms: D000328:Adult; D015992:Body Mass Index; D003924:Diabetes Mellitus, Type 2 / Q000453:epidemiology* / Q000209:etiology; D005260:Female; D006801:Humans; D008597:Menstrual Cycle; D009765:Obesity; D009839:Oligomenorrhea / Q000150:complications* / Q000503:physiopathology; D011446:Prospective Studies; D012044:Regression Analysis; D012307:Risk Factors