Further regulation of blood glucose monitor use by non-diabetics is needed

A new narrative review led by researchers from University College London (UCL) and Birmingham Children's Hospital has found a lack of evidence supporting the effectiveness of continuous glucose monitoring (CGM) in people without pre-existing diabetes (PNLD).

In a study published in 2011, Diabetes medicationsThe researchers conclude that there is currently little published evidence on the accuracy of CGM in measuring blood glucose levels in people with PNLD, and also insufficient evidence on the health benefits or usefulness of such information. The researchers also suggest that CGM may have unintended adverse health effects in this user group, and they are now calling for better regulation.

In recent years, CGMs have revolutionized the treatment of type 1 diabetes and are being used effectively by type 2 diabetes patients on insulin therapy. Originally developed for diabetes patients, the device is worn on the body to monitor blood glucose levels in real time and transmits that information to the type 1 diabetes patient's insulin pump, which administers the amount of insulin needed to keep blood glucose levels within a prescribed range.

For people with diabetes, CGM is less invasive than traditional testing methods such as regular finger-prick blood tests and can provide real-time insight into trends in blood sugar levels.

Recently, however, CGMs have been increasingly marketed to PNLDs for non-medical indications, such as health, wellness, and lifestyle management, with some companies offering advice on how to manage blood glucose levels and “blood sugar spikes.”

Commenting on the current interest in CGM, senior author and nutritionist Dr Adrian Brown (UCL School of Medicine) said: “Several health companies are now using CGM as part of paid programmes aimed at providing personalised nutritional information.

“Some argue that a person's diet or activity needs to be adjusted to keep blood glucose levels at 'normal' levels. However, normal blood glucose levels vary from person to person and over time for the same person, and the accuracy of CGMs varies between CGM models.”

“With this in mind, we wanted to know what research has been done about the use of CGM in people without diabetes.”

In this narrative review, a team from UCL and Birmingham Children's Hospital searched online databases (PubMed, Medline, Embase and Cochrane Library) spanning the years 1980 to 2023 and found 25 studies that investigated the utility and performance aspects of CGM in PNLD.

The researchers then sought to determine what evidence there is on how effective CGMs are at measuring blood glucose levels, blood glucose fluctuations, and blood glucose elevations in PNLD, and whether there is any research on the impact of CGM use on eating behaviors.

The review concluded that there is a lack of consistent, high-quality evidence supporting the use of CGM in PNLD. For example, there is little evidence to show how accurate CGMs are in measuring blood glucose levels or detecting changes in PNLD, and there is a lack of research on the value and usefulness of CGM data obtained in PNLD.

The study also found evidence that CGM use in people with PNLD may cause anxiety about what is normal in terms of diet and blood sugar levels, which the researchers say could put them at risk of developing eating disorders such as orthorexia (an unhealthy obsession with eating “pure” foods).

Another previous review by the authors referenced in this paper looked at the regulation of CGM in people with diabetes and found that no specific statutory guidance exists.

“Personal health programmes offered by private healthcare providers have some benefits, such as getting people to think about what and how much they are eating, but the reality is there is a lack of similar health outcomes data on CGM use in people without diabetes,” said Dr Brown, from the Obesity Research Centre at University College London.

“This review sheds light on the concept of ‘abnormal blood glucose levels’, the accuracy of CGM data, and the impact on behavior change when used by people without diabetes.

“Currently, there are significant questions about how much guidance these health companies are providing to customers to help them interpret their blood glucose data, and what scientific evidence this guidance is based on. This leaves customers to interpret what changes in blood glucose levels mean, creating the risk that they may misinterpret the data and unnecessarily avoid certain foods.”

“CGMs that are accurate to within 20% of actual blood glucose values ​​at least 95% of the time are currently market-leading performance and can be invaluable in helping people with diabetes make everyday treatment decisions,” said co-author John Pemberton, member of the International Federation of Clinical Chemistry and Laboratory Medicine Working Group on CGM and specialist paediatric diabetes nutritionist at Birmingham Children's Hospital.

“However, regulations regarding CGM for people with diabetes are vague both nationally and internationally, making it difficult to know whether available CGMs meet this level of accuracy. This is why the IFCC CGM Group is pushing for the establishment of an international standard.”

“For people without diabetes, the situation is even more uncertain. There is little solid information about whether CGM can achieve the required accuracy in this population.”

“Normal blood glucose levels for people without diabetes range from 3.3 to 7.8 mmol/L, and the most accurate CGMs are often only 20% accurate, meaning that even when your actual blood glucose level is within the normal range, the most accurate CGM devices will give you a reading between 2.6 and 9.4 mmol/L. Such discrepancies can lead to unintended stress and psychological and behavioral effects.”

“Although CGMs for non-diabetics show promise, their accuracy, regulatory standards, and the psychological effects of false hyperglycemia and hypoglycemia are not well understood. Yet CGMs are being heavily promoted without addressing these issues.”