Women who experience menopause before age 46 years or after age 55 years or who have a reproductive span shorter or longer than 30 to 45 years are at increased risk for developing type 2 diabetes, according to an analysis of Women’s Health Initiative data.
Age at menarche and menstrual cycle regularity were not associated with diabetes risk.
Erin S. LeBlanc, MD, MPH, investigator with the Kaiser Permanente Center for Health Research in Portland, Oregon, and colleagues evaluated data from the WHI on 124,379 postmenopausal women aged 50 to 79 years to assess the relationship between reproductive history and the risk for developing type 2 diabetes.
Participants completed questionnaires at baseline, and researchers used responses to determine age of menarche and final menstrual period and history of irregular menses. Reproductive span was calculated by subtracting age of menarche from final menstrual period. Follow-up was conducted for a mean 12.2 years. Reproductive-period duration was categorized based on length in years: less than 30 years, 30 to 35 years, 36 to 40 years, 41 to 45 years and more than 45 years.
New diagnoses of type 2 diabetes were reported by 11,262 participants during 974,714 person-years of follow-up. After adjustment for age, participants with a reproductive period of less than 30 years had a 37% increased risk for developing type 2 diabetes compared with participants with a reproductive period of 36 to 40 years (HR = 1.37; 95% CI, 1.3-1.45); participants with a reproductive period of more than 45 years had a 23% greater risk compared with those with a reproductive period of 36 to 40 years (HR = 1.23; 95% CI, 1.12-1.37).
Compared with participants who had their final menstrual period from age 46 to 55 years, participants who experienced their last menstrual period before age 46 years were 25% more likely to develop type 2 diabetes (HR = 1.25; 95% CI, 1.2-1.3), and those who experienced their last menstrual period after age 55 years were 12% more likely (HR = 1.12; 95% CI, 1.06-1.18).
The risk for type 2 diabetes was greater among women who experienced their first menstrual period before age 12 years compared with those who experienced it at age 12 years (HR = 1.14; 95% CI, 1.08-1.2), but the risk for type 2 diabetes was decreased among participants who experienced their first menstrual period after age 12 years (HR = 0.93; 95% CI, 0.89-0.97). After adjustment for variables including demographics, history of hormone therapy and pregnancy, and physical activity, among others, the relationships between age at menarche and diabetes risk were no longer significant.
Compared with participants with regular menstrual cycles, those with irregular cycles had an 11% increased risk for type 2 diabetes (HR = 1.11; 95% CI, 1.04-1.19), but the association between cycle regularity and type 2 diabetes was not significant after full adjustment.
“Our study suggests the optimal window for menopause and diabetes risk is between the ages of 46 and 55,” LeBlanc said in a press release. “Women who start menopause before or after that window should be aware that they are at higher risk, and should be especially vigilant about reducing obesity, eating a healthy diet and exercising. These lifestyle changes will help to reduce their risk for type 2 diabetes.” – by Amber Cox