A CGM, or continuous glucose monitor, is a slim glucose sensor applied to the belly or arm, with a very small needle (described by Dexcom, one of the companies that makes them, as “soft and flexible like a kitten’s whisker”) to continuously measure glucose levels in the interstitial fluid of the tissue just below the skin. Newer monitors are worn 10-14 days and can now send data wirelessly to an app on your phone.
CGMs have good evidence behind them for use in type I diabetes, where they have been able to reduce the number of fingersticks needed for close monitoring of blood sugar levels in patients taking insulin throughout the day. There is less data supporting CGM use in type II diabetes or pre-diabetes. An article by the assistant medical editor of American Family Physician (journal of the American Academy of Family Physicians), Dr. Allen Shaughnessy, and colleagues summarized:
“Continuous glucose monitoring has a few potential advantages. The ability to get in-the-moment glucose readings without a finger stick may be appealing to patients. Physicians may appreciate the longitudinal data on blood glucose excursions that the devices offer. However, as with other technology introduced into health care, the promise that more data will lead to better patient outcomes has not yet been realized. Most people with type 2 diabetes do not require self-monitoring of blood glucose, and unnecessary monitoring not only wastes money but can negatively impact quality of life. Until we have research supporting continuous glucose monitoring for patients with type 2 diabetes, especially those not receiving regular insulin injections, there are no patient-oriented benefits to justify its great expense and additional hassles for patients and physicians.”
However, I tend to agree with the sentiments of UCSF’s Vice President of Digital Health and Associate Professor of Endocrinology, Aaron Neinsten, who recently wrote,
“With rapidly improving CGM technology, wireless data upload, lower-cost CGM devices, and the availability of digital coaching tools, we believe the time is ripe for CGM use in a much broader population, including those with T2D who are on oral medications and those with prediabetes. Although additional studies will need to be done to demonstrate benefit in these populations, costs will likely continue to fall and technology will continue to improve, only further strengthening the value proposition for wider CGM use.”
In today’s era of wearable technology and app-based health coaching, the problem of what to do with all of the data generated by CGMs is being tackled by a number of new tech-enabled digital coaching services. For those interested, check out more on January.AI, Levels Health and NutriSense. Easily visible trends and trajectories along with health coaches for interpretation and motivation can help a person understand their own glycemic response in a more meaningful way. Patients can observe which foods and exercises affect them the most, allowing patients to learn about their own bodies and physiologic responses in real-time, iterating on the immediate feedback to create lasting changes. For more interesting information on the topic, check out this part two of a three-part series on glucose and metabolic health by nutritionist Jill Goldring, Master’s in Nutrition Science and Policy from Tufts University Friedman School of Nutrition Science and Policy, featured by our friend Jeanne Rosner’s Soul Food Salon newsletter.
Jennifer Abrams, MD, November 2, 2021