Regulatory and Psychological Considerations for CGM Use in Non-Diabetics

A new narrative review by researchers from UCL and Birmingham Children’s Hospital has found there is a lack of evidence to support the effectiveness of continuous glucose monitoring (CGM) in people without diabetes (PNLD).

In a study published in Diabetes medicineThe researchers conclude that there is currently little published evidence on how accurate CGM is in measuring blood glucose levels in PNLD, nor is there sufficient evidence on what health benefits or usefulness such information may provide. The researchers also suggest that CGM may have unintended adverse health effects in this group of users and are now calling for better regulation.

In recent years, CGM has helped transform the treatment of type 1 diabetes and has been used with great success by people with type 2 diabetes who use insulin therapy. The devices, originally developed for people with diabetes, are strapped to the body and monitor blood glucose levels in real time, sending information to an insulin pump in people with type 1 diabetes, which delivers the right amount of insulin needed to keep blood glucose levels within a specific range.

For people with diabetes, CGM systems are less intrusive and allow for real-time tracking of glucose trends compared to older testing methods such as regular finger prick blood tests.

Recently, however, CGM systems are increasingly being marketed as PNLD devices for non-medical indications, such as health, wellness, and lifestyle management, with some companies providing advice on how to manage glucose levels or “glucose spikes.”

Explaining the current interest in CGM systems, senior author and dietitian Dr Adrian Brown (UCL Division of Medicine) said: “Several healthcare companies are now using CGM systems as part of paid programmes to provide people with personalised nutrition information.

“Some claim to adjust a person’s diet and activity to help maintain blood glucose levels in a ‘normal’ range. However, what constitutes normal blood sugar levels varies between individuals and within the same individual at different times, and the accuracy of CGM varies between CGM models.

“With that in mind, we wanted to see what research had been done on the use of CGM in people who don’t have diabetes.”

In this narrative review, a team from UCL and Birmingham Children’s Hospital searched online databases (PubMed, Medline, Embase and the Cochrane Library) from 1980 to 2023 for studies examining aspects of the utility and effectiveness of CGM in PNLD. They found 25 relevant studies.

The researchers then examined whether there was evidence, if any, on the effectiveness of CGM in measuring glucose levels, glucose variability, and elevated glucose levels in patients with PNLD, as well as whether there were studies on the effect of CGM use on eating behaviors.

The review concludes that there is a lack of consistent and high-quality evidence to support the use of CGM in PNLD. For example, there is little evidence on how accurate CGM is in measuring blood glucose levels or detecting changes in PNLD, nor is there sufficient research on the value and utility of CGM data obtained in PNLD.

The review also found evidence that using CGM in PNLD can cause anxiety about what is normal in terms of diet and blood sugar levels. The researchers say this could put them at risk for developing eating disorders such as orthorexia (an unhealthy obsession with eating “clean” foods).

An earlier, separate review by the authors, referenced in this article, examined the regulation of CGM in people with diabetes and did not identify any specific statutory guidelines.

While personalized health programs offered by commercial providers have some benefits, including making people think about what and how much they eat, the fact is that we do not have the same data on the health effects of CGM use as we do for people without diabetes.

This review discusses the concept of “abnormal glucose levels”, the accuracy of CGM data, and the impact of CGM on behavioral change in people without diabetes.

There are big questions now about how much guidance these healthcare companies are giving consumers to help them interpret their glucose data, and what scientific evidence is behind that guidance. This can leave consumers left to interpret what their blood glucose fluctuations mean, which can leave them at risk of misinterpreting the data and needlessly avoiding certain foods.”

Dr Adrian Brown, UCL Centre for Obesity Research

Co-author John Pemberton, a consultant paediatric dietitian in diabetes at Birmingham Children’s Hospital who sits on the International Federation of Clinical Chemistry (IFCC) and Laboratory Medicine Working Group on CGM, said: “CGM systems that are accurate to within 20% of actual blood glucose levels at least 95% of the time are at the top of the list of best-in-class solutions on the market and are extremely helpful for people with diabetes in making day-to-day management decisions.

“However, regulations regarding CGM for people living with diabetes are ambiguous both nationally and internationally, making it difficult to determine whether available CGMs meet this level of accuracy. That is why the IFCC CGM group is pushing for an international standard.

“The situation is even more uncertain for people without diabetes. We have little solid information about whether CGMs achieve the required accuracy in this population.

“Normal glucose levels in non-diabetics range from 3.3 to 7.8 mmol/L, and the most accurate CGMs have a 20% margin of accuracy in most cases. This means that the most accurate CGM devices will display readings between 2.6 and 9.4 mmol/L, even when the actual glucose level is within the normal range. Such discrepancies can lead to unintended stress and potential psychological and behavioral implications.”

“Although CGM for nondiabetics shows promise, accuracy, regulatory standards, and the psychological effects of false highs and lows are not well understood. Despite this, CGM is heavily promoted without mentioning these problems.”