Risk for type 2 diabetes (T2D) was elevated among women who had irregular and long menstrual cycles throughout their lifetime. These findings from a prospective cohort study were published in JAMA Network Open.
Researchers used data from the Nurses’ Health Study II, which was an ongoing cohort study beginning in 1989. Participants (N=75,546) were women working in the nursing profession who were assessed biennially for general health characteristics. The women self-reported regularity and length of their menstrual cycles.
At baseline, the women had a mean age of 37.9 years (standard deviation [SD], 4.6). Stratified by cycle regularity, women with irregular or no period had higher average body mass indexes (28.1 vs 24.9 kg/m2), caloric intake (1825.5 vs 1798.5 kcal/day), likelihood of smoking (11.9% vs 10.3%), and family history of diabetes (19.1% vs 15.6%) and lower alcohol consumption (2.6 vs 3.2 g/day) and mean Alternate Healthy Eating Index (AHEI)-2010 diet scores (46.9 vs 48.2).
During the follow-up, 7.4% of women developed T2D. After adjusting for lifestyle factors, increased risk for diabetes was associated with women who had no or irregular periods when they were ages 14 to 17 years (32%; 95% CI, 22%-44%), 18 to 22 years (41%; 95% CI, 23%-62%), or 29 to 46 years (66%; 95% CI, 49%-84%).
Women who reported a cycle length that lasted 40 days or more or was too irregular to estimate during ages 18 to 22 years or 29 to 46 years had an increased risk of 37% (95% CI, 19%-57%) and 50% (95% CI, 36%-65%) for T2D, respectively. Women who used oral contraceptives at ages 14 to 17 years (hazard ratio [HR], 1.12; 95% CI, 1.01-1.24; P =.04) or 18 to 22 years (HR, 1.22; 95% CI, 1.12-1.33; P <.001) were at increased risk for T2D.
During the reproductive lifespan of these women, those with cycles that changed from less than 32 days to 32 days or longer (HR, 1.62; 95% CI, 1.39-1.88) or were consistently irregular (HR, 1.55; 95% CI, 1.34-1.80) were at the highest risk for T2D.
This study may be biased by the self-reported design of data collection, in which measurement error could not be fully excluded.
These data indicated that the regularity of menstrual cycles during the reproductive life of a woman may be a significant and independent predictor for T2D risk. Further study is needed to assess this relationship.
Disclosure: One author declared affiliations with the pharmaceutical industry. Please see the original reference for a full list of authors’ disclosures.
Wang YX, Shan Z, Arvizu M, et al. Associations of menstrual cycle characteristics across the reproductive life span and lifestyle factors with risk of type 2 diabetes. JAMA Netw Open. 2020;3(12):e2027928. doi:10.1001/jamanetworkopen.2020.27928