Menstrual patterns and risk of adult-onset diabetes mellitus

We examined the association between menstrual patterns and risk of developi ng adult-onset diabetes in a prospective study of 668 white, college-educat ed women who completed menstrual diaries throughout their reproductive year s. We calculated summary measures of cycle length and variability and bleed ing duration for ages less than or equal to 22, 23-27, 28-32, and 33-37 yea rs. The analysis included 35,418 person-years of follow-up and 49 self-repo rted cases of diabetes (median age at diagnosis, 63 years). There was no as sociation between diabetes risk and age at menarche, mean cycle length, cyc le variability, or frequency of long cycles (>42 days). Longer bleeding per iods in the mid- and late reproductive years were somewhat associated with an increased risk of diabetes (adjusted rate ratio 1.4, 95% confidence inte rval 1.0-1.8 per day increase in bleeding duration for menses during ages 2 8-32). These results do not support the association of long or irregular me nstrual cycles with post-menopausal diabetes incidence, but do suggest a po ssible association of longer bleeding duration with subsequent onset of dia betes. (C) 2000 Elsevier Science Inc. All rights reserved.