Researchers Present Ranges of Normal Glucose Levels Among Non-Diabetic Adults Wearing Continuous Glucose Monitors

New continuous glucose monitoring sensors (small sensors that penetrate the skin to measure glucose levels in real time) are now hitting the wearables market for use among individuals without diabetes. Despite a lack of research showing that using these sensors improves health outcomes in individuals without diabetes, there is a growing interest among this population. To date, there have been no large studies describing normative glucose ranges for non-diabetics.

"Many individuals without diabetes are becoming interested in using continuous glucose monitors and two major manufacturers of glucose monitoring sensors, Dexcom and Abbott, just launched products that can now be bought over the counter. It is important for people to know what the 'normal' ranges of glucose levels are so they can interpret their own continuous glucose monitor data," explained Nicole L Spartano, Ph.D., assistant professor of medicine at the Boston University Chobanian & Avedisian School of Medicine.

Spartano is the corresponding author in a new study by researchers at the school that found that non-diabetic individuals using continuous glucose monitoring sensors spend a much larger period of the day with elevated glucose levels than was previously thought. Not only do these findings contribute to the understanding of the physiological glucose range of people without diabetes, but they can also serve as a reference for both patients using these sensors and their clinicians.

These findings appear online in the Journal of Clinical Endocrinology & Metabolism.

The researchers used data from the Framingham Heart Study Third Generation, a group of middle-aged and older adults. Participants wore the Dexcom G6 Pro for at least seven days on their arm or abdomen. The sensors measured glucose levels in the interstitial fluid (under the skin) every five minutes throughout their participation.

They observed that normoglycemic participants (without traditional diabetes risk factors: elevated blood glucose or HbA1c) spent on average, approximately three hours/day (12.1% of the time) with glucose levels >140mg/dL and many even experienced glucose levels >180mg/dL. Previous research from much smaller studies suggested that individuals with normoglycemia spent very little time above even the 140mg/dL glucose range.

Another important finding was that the majority of participants with normoglycemia and prediabetes had a similar range of mean CGM glucose (100–140mg/dL). Therefore, mean glucose may not be a factor that can help distinguish those with or without prediabetes, despite the fact that those with prediabetes have high blood biomarkers and higher levels of other CGM metrics. For example, those with prediabetes spent, on average, greater than five hours/day with CGM glucose >140mg/dL, while individuals with diabetes often spend more that half of their day above that level.

According to the researchers, observing a wide range of possible glucose levels in a population without diabetes suggests that it may be possible to use continuous glucose monitors to predict who may go on to develop diabetes in the future.

"It is important to understand the physiological time spent in specific ranges of CGM glucose for individuals without diabetes, which could serve as targets for individuals with diabetes or prediabetes," she adds.