CGM metrics may not provide accurate health information for people without diabetes

Key Takeaways:

• Those without diabetes had a 0.59% higher Glucose Management Index than laboratory-measured HbA1c using CGM.
• More research is needed to analyze whether CGM use benefits people without diabetes.

Continuous glucose monitoring has been strongly established as beneficial in helping diabetics understand their glucose profile, but it is not yet clear whether these metrics translate to people without diabetes.

In a study published by Dr Diabetes Technologies and Therapeutics, researchers found a discrepancy between the glucose management indicator (GMI), a CGM metric that estimates HbA1c, and laboratory-measured HbA1c. In an analysis of data from 153 nondiabetic children and adults who wore a masked CGM for 10 days, the cohort mean GMI was 0.59% higher than laboratory-measured HbA1c. Additionally, 71% of participants had a difference of 0.4% or more between GMI and HbA1c, a percentage higher than the 39% of adults with diabetes who reported a difference between GMI and HbA1c of 0.4% or more. In 2018.

Viral N Shah, MD, The research is important because the number of people without diabetes using CGMs has increased recently, said the study’s lead author, who is an associate professor of medicine and pediatrics in the adult clinic of the Barbara Davis Center for Diabetes at the University of Colorado Anschutz Medical Campus. year

“Based on the results of our study, it would not be appropriate to use GMI as a substitute for HbA1c in people without diabetes,” Shah told Helio. “GMI will overestimate HbA1c by about 0.6%, and it is possible that it may misclassify many people without diabetes as prediabetes.”

Healy also recently spoke with Shah about the rise in CGM use among people without diabetes, why people without diabetes should be careful when interpreting CGM data, and whether new or revised metrics could benefit people without diabetes.

helio: Your study notes that CGM use is increasing among people without diabetes. Why do more people without diabetes use CGM?

Shah: There are many start-up companies that promote CGM as an adjunct to lifestyle changes to improve people’s well-being and metabolic health, prevent the progression of prediabetes to diabetes, or lose weight. This has been going on for a while now, but recently there has been a further proliferation of these companies.

Hello: Why was it important to analyze the difference between GMI and HbA1c in people without diabetes? and WHat is some reason There was such a large discrepancy between GMI and HbA1c?

Shah: With the increase in CGM use by people without diabetes, it is expected that people will use CGM metrics, including GMI, to assess their health. GMI is a mathematical equation for estimating HbA1c from sensor glucose. The GMI equation was derived using sensor glucose from people with type 1 and type 2 diabetes. Therefore, it is possible that GMI may not work well for people without diabetes. We hypothesized that GMI may overestimate HbA1c for people without diabetes and, therefore, conducted our study.

The GMI was derived for a population with diabetes with a mean HbA1c of 7.3%, where you would expect a higher HbA1c than people without diabetes. Thus, in our study we found a higher discrepancy between GMI and HbA1c for people without diabetes than for people with diabetes.

when the first Consensus is published Journal of Diabetes Science and Technology Timed in 2013 and then changed in 2017 and 2019, the emphasis was entirely on CGM use in people with type 1 and type 2 diabetes. They wanted to make sure we were telling people why these metrics were important, what the goals and recommendations were. It was all based on the management of type 1 and type 2 diabetes, with no emphasis on recommendations to develop metrics useful for people without diabetes. But may come in near future. At the Advanced Technologies and Treatments for Diabetes meeting it was discussed that we need to start refining some of the metrics and give people more clarity that these metrics may be different for people without diabetes. have speed

Helio: For people without diabetes, will experts look at adjusting reference ranges for existing CGM metrics or will they create new metrics?

Shah: It all depends on the consensus and who the experts are in that consensus group. Remember, consensus is not an evidence-based guideline, it is a starting point. Then, based on more evidence, they’re going to revise their recommendations.

We published data on CGM across the lifespan in individuals without diabetes. We also published some data on the response to exercise and different foods in people without diabetes. We are trying to build at least some literature around this so that it can be helpful in determining normal reference ranges in the future.

Helio: Have there been large studies analyzing whether CGM is beneficial for lifestyle or dietary changes in people without diabetes?

Shah: No not really. Some small-scale studies have been presented during various meetings that have not been published, but they have shown some benefits. A small study from the University of Michigan documented a small change in some metrics over time in people with prediabetes. But there isn’t a really good phase 3 study with definitive results. One result is, for example, if I use CGM in people with overweight or obesity and weight loss is compared with a control group. If you claim it can improve athletic performance, is there any research around that part? If you are saying that it improves metabolic health, are there any studies that have a specific result? We need to do a lot of research before we can say that CGM is going to be useful for people without diabetes.

Hello: Should people without diabetes use CGM at all? If they use CGM, what should they keep in mind when interpreting the data?

Shah: In my opinion, CGM can be helpful in making lifestyle and dietary changes and improving lifestyle adherence. However, we need more studies before I recommend CGM for people without diabetes.

If people without diabetes use CGM, they should remember that most CGM metrics, such as time in range or time below limit or GMI, were developed for people with diabetes and not people without diabetes. People without diabetes should not use these metrics to assess their health status or changes in health status.

References:

• Bergenstal RM, et al. J Diabetes Sci Technol. 2013;doi:10.1177/193229681300700234.
• Bergenstal RM, et al. Diabetes care. 2018; doi:10.2337/dc18-1581.
• DuBose SN, et al. J Diabetes Sci Technol. 2021;doi:10.1177/1932296820905904.
• Shah VN, et al. Diabetes Technol Ther. 2023;doi:10.1089/dia.2022.0544.
• Shah VN, et al. J Clin Endocrinol Metab. 2019;doi:10.1210/jc.2018-02763.
• Yost O, et al. JMIR Diabetes. 2020;doi:10.2196/21551.

For more information:

Viral Shah, MD, Can be contacted at [email protected].