Reproductive History and Type 2 Diabetes Risk

Women with too short or too long reproductive periods may have an increased risk of developing diabetes, according to a new study.

The results suggest that women with shorter and longer reproductive periods may benefit from lifestyle counseling about the risks of diabetes.

“Our study found that both shorter and longer reproductive-duration lengths are associated with increased risk of type 2 diabetes,” state the authors, led by Erin S. LeBlanc, MD, MPH, of the Kaiser Permanente Center for Health Research, Portland, OR. “This suggests that lifetime estrogen exposure may play a role in the development of type 2 diabetes - there may be an ‘optimal' amount of estrogen exposure for metabolic functioning, although exogenous estrogen may have different effects due to different route, dose, and timing of administration.”

The authors conducted a prospective cohort analysis of 124,379 postmenopausal women aged 50 to 79 years from the Women's Health Initiative. They determined age of menarche and final menstrual period, and history of irregular menses from questionnaires at baseline, and calculated reproductive length from age of menarche and final menstrual period. The presence of new onset type 2 diabetes was self-reported.

Using age-adjusted models, they found that women with the shortest (less than 30 years) reproductive periods had a 37% greater risk of developing type 2 diabetes than women with medium-length reproductive periods (from 36 to 40 years). Surprisingly, women with the longest (45 or more years) reproductive periods had a 23% higher risk than women with medium-length periods.

These associations were attenuated after full adjustment for the shortest and longest reproductive periods as compared with medium duration.

“Those with a final menstrual period before age 45 and after age 55 had an increased risk of diabetes compared to those with age of final menstrual period between 46 and 55 years,” the authors state. Timing of menarche and cycle regularity was not associated with risk after full adjustment.

“The Women’s Health Initiative provides a unique setting to evaluate the associations between reproductive characteristics and diabetes because of its large size, robust characterization of reproductive histories, long duration of follow-up, and ability to prospectively ascertain type 2 diabetes,” says JoAnn V. Pinkerton, MD, Executive Director of The North American Menopause Society.

She notes that low estrogen negatively affects body fat distribution and fat accumulation, both contributors to type 2 diabetes, but a later age of menopause has not previously been associated with increased risk.

Reproductive period length and age of final menstrual period may be important factors to add to risk assessments when clinicians counsel women about diabetes and the need to make lifestyle changes, such as weight loss, improved diet, and increased exercise, which have been proven to decrease risk, says Pinkerton.

“Given the high prevalence of diabetes in postmenopausal women, those with shorter and longer reproductive periods may benefit from lifestyle counseling. Future research should focus on ways to prevent type 2 diabetes in women at risk as they age,” says Pinkerton.

Reference: LeBlanc ES, et al. Reproductive history and risk of type 2 diabetes mellitus in postmenopausal women: findings from the Women's Health Initiative. Menopause. 2016 Jul 25.