Advertisement
ADVANCED SEARCH

This Article Figures Only Full Text Full Text (PDF) Résumé Correction (v178,p598) Submit a response Alert me when this article is cited Alert me when eLetters are posted Alert me if a correction is posted Citation Map Services Email this article to a friend Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via Google Scholar Google Scholar Articles by Ray, J. G. Articles by Michels, K. B. Search for Related Content PubMed PubMed Citation Articles by Ray, J. G., MD MSc Articles by Michels, K. B., ScD PhD Related Collections Diabetes Obesity Related Articles

Breast size and risk of type 2 diabetes mellitus

From the Departments of Medicine, Obstetrics and Gynecology, and Health Policy Management and Evaluation, and the Li Ka Shing Knowledge Institute, St. Michael's Hospital, University of Toronto (Ray), Toronto, Ont.; the Department of Epidemiology, Harvard School of Public Health (Mohllajee), Boston, Mass.; the Department of Nutrition, Harvard School of Public Health, and the Department of Nutrition and Health, Institute for Health Sciences, Vrije Universiteit (van Dam), Amsterdam, the Netherlands; the Channing Laboratory, Department of Medicine, Brigham and Women's Hospital, Harvard Medical School, and the Department of Epidemiology, Harvard School of Public Health (Michels), Boston, Mass.

Correspondence to: Dr. Joel G. Ray, Department of Medicine, St. Michael's Hospital, 30 Bond St., Toronto ON M5B 1W8; fax 416 864-5485; rayj{at}smh.toronto.on.ca

Background: Elevated waist circumference and body mass index (BMI), both traditional measures of obesity, are accepted risk factors for type 2 diabetes mellitus. Girls who are obese experience earlier onset of puberty and possibly greater breast development. We sought to evaluate whether a woman's breast size in late adolescence is associated with an increased risk of type 2 diabetes mellitus in adulthood.

Methods: In conjunction with the ongoing Nurses' Health Study II, which began to study risk factors for breast cancer among women in 1989, we conducted a prospective cohort study involving 92 106 of the participants. We assessed the risk of type 2 diabetes mellitus in relation to self-reported bra cup sizes, categorized as A, B, C and D cups, among participants at age 20.

Results: The mean age of participants at baseline was 38.1 years. A total of 1844 new cases of type 2 diabetes mellitus arose at a mean age of 44.9 years during 886 443 person-years of follow-up. Relative to bra cup size A, the respective age-adjusted hazard ratios (and 95% confidence intervals [CIs]) were 2.30 (1.99–2.66) for B cup, 4.32 (3.71–5.04) for C cup and 4.99 (4.12–6.05) for D cup. Upon further adjustments for age at menarche, parity, physical activity, smoking status, diet, multivitamin use, family history of diabetes mellitus, BMI at age 18 and current BMI, the corresponding hazard ratios (and 95% CIs) were 1.37 (1.18–1.59) for B cup, 1.80 (1.53- 2.11) for C cup and 1.64 (1.34–2.01) for D cup. The addition of waist circumference to this model minimally changed the hazard ratios (and 95% CIs): 1.32 (1.14–1.53) for B cup, 1.71 (1.46–2.01) for C cup and 1.58 (1.29–1.94) for D cup.

Interpretation: A large bra cup size at age 20 may be a predictor of type 2 diabetes mellitus in middle-aged women. Whether this relation is independent of traditional indicators of obesity remains to be determined.

HOME	CURRENT ISSUE	PAST ISSUES	COLLECTIONS	HELP	SEARCH
Copyright 1995-2008, Canadian Medical Association. All rights reserved. ISSN 1488-2329 (e) 0820-3946 (p) All editorial matter in CMAJ represents the opinions of the authors and not necessarily those of the Canadian Medical Association.