Studying the link between the menstrual cycle and blood sugar

November 20, 2023—Menstrual cycle phases can influence individuals’ blood glucose levels—raising new possibilities for diabetes care, according to new research from Harvard T.H. Chan School of Public Health.

The research was conducted as part of the Apple Women’s Health Study (AWHS), a collaboration between the tech company and researchers at Harvard Chan School. Using health data collected via participants’ iPhones and Apple Watches, the study aims to uncover new information about how demographic and lifestyle factors impact menstrual cycles and gynecologic conditions such as infertility, menopause, and polycystic ovary syndrome.

To learn more about the relationship between the menstrual cycle and blood glucose levels, researchers looked at data from 231 study participants who shared at least 100 days’ worth of data from continuous glucose monitors, across at least six consecutive menstrual cycles. The analysis, which included data from 1,982 menstrual cycles, showed that during the first half of the menstrual cycle—the follicular phase, associated with menstruation, when estrogen increases and progesterone decreases—participants spent 68.5% of the day at a healthy blood sugar level. Comparatively, during the second half of the menstrual cycle—the luteal phase, associated with ovulation, when estrogen decreases and progesterone increases—participants spent 66.8% of the day at a healthy blood sugar level. The researchers also found that during the follicular phase, participants experienced high blood sugar levels less often than during the luteal phase.

Shruthi Mahalingaiah, co-principal investigator of the AWHS and an assistant professor in the Department of Environmental Health at Harvard Chan School, said in a November 12 PC Mag article that the findings may prove particularly important to people with diabetes. “This preliminary analysis may pave the way for a more in-depth examination of the relationship between menstrual cycle phases and glucose levels, offering potential implications for diabetes management,” she said.

Learn more about the research: World Diabetes Day: glucose response to activity and the menstrual cycle

Read the PC Mag article: Study: Close Your Apple Watch Rings for Better Blood Sugar Levels