Landmark Apple health studies share new glucose control insights on World Diabetes Day

Two public landmark health studies led by Apple on Tuesday shared new findings that reinforce the benefits of physical activity on glucose and highlight some of the many challenges people living with diabetes face every day, including maintaining a target range throughout a menstrual cycle.

This year, researchers from Harvard’s Brigham and Women’s Hospital and Harvard’s T.H. Chan School of Public Health collaborated on a study update that evaluates the effects of physical activity and the menstrual cycle on glucose.  

Released on the World Diabetes Day that was observed on Tuesday, the analyses used data from both the Apple Heart and Movement Study (AHMS) and the Apple Women’s Health Study (AWHS).

As part of the study, as participants increased either the average duration of exercise or the average number of steps taken on a given day, there was a corresponding increase in the average percentage of time glucose fell within the target range of 70-180 mg/dL. 

People who exercised more than 30 minutes per day spent 78.8 per cent of day in the target range of 70-180 mg/dL.

Participants who identified as female and walked more than 10,000 steps per day saw the most time spent in the target range of 70-180 mg/dL, compared to 76.4 per cent of participants who identified as male. 

On menstrual cycle, analyses of glucose levels across 1,982 menstrual cycles highlighted a slight increase in time spent within the target range of 70-180 mg/dL during the follicular phase when progesterone levels are lower (68.5% of day) compared to the luteal phase (66.8% of day). 

Polycystic ovary syndrome (PCOS) and a body mass index greater than 30kg/m2 can also increase resistance to insulin and subsequently glucose levels, the findings showed. 

Researchers reinforced that early detection of diabetes and intensive glucose management can reduce the risk and severity of many complications.

Shruthi Mahalingaiah, assistant professor of environmental, reproductive, and women’s health at the Harvard T.H. Chan School of Public Health, said that in a preliminary analysis, “our research team has identified an intriguing pattern in continuous glucose measurements across the menstrual cycle among people with regular cycles”. 

“During the follicular phase, which is characterised by higher estrogen levels and low progesterone levels, we’ve observed a slight increase in the time spent within the target glucose range. This discovery holds the potential to significantly improve diabetes management by providing valuable insights for optimising blood sugar control,” Mahalingaiah added.

According to Calum MacRae, a cardiologist and professor of medicine at Harvard Medical School, and principal investigator of the Apple Heart and Movement Study at Brigham and Women’s Hospital, empowering users to move their personal physiology in the right direction is a fundamental foundation of precision health and medicine. 

“Apple Watch enables users to determine how best to improve their cardiometabolic risk. These data demonstrate that exercising at the right levels can improve how each of us deal with metabolic challenges to reduce the risk of diabetes or to improve the control of diabetes if it does develop,” MacRae explained.

Based on these new research insights — as well as additional input from people with diabetes — Apple highlighted five features on iPhone and Apple Watch that can be useful for those with diabetes, including Activity, Cycle Tracking, Sleep, Medical ID, and third-party apps. 

While the Activity app allows you to set goals, record duration, and receive reminders about exercise targets, you can track your menstrual cycle, receive period predictions, as well as retrospective estimates of when you likely ovulated with Cycle Tracking. 

With the Sleep app, you can set a sleep schedule, receive reminders when to wind down, and track how well you are doing in meeting your sleep goals. 

In the Health app, you can update your Medical ID to include information about diabetes and medications, which can be shared in various ways to help in an emergency. 

There are also several third party iOS apps affiliated with glucose meters, including CGMs, that help users measure and track their glucose.