Continuous blood glucose monitoring devices: More harm than good

Continuous glucose monitor (CGM). (Source: Sydenham Clinic)

Originally designed to save the lives of millions of people with diabetes, CGMs are now becoming a trendy accessory for those pursuing a “maximum health” lifestyle, even if they’re perfectly healthy. But is this a giant leap forward for personalized medicine, or just a risky fad?

With more than 38 million Americans living with diabetes — a disease that occurs when blood sugar levels are high because the body doesn't produce enough insulin or becomes resistant to insulin, causing serious damage to the heart, kidneys and vision — CGM is a revolutionary tool.

Instead of having to prick the blood repeatedly throughout the day, users simply attach a small sensor patch to their arm or abdomen. A small needle gently penetrates the skin, measuring the glucose concentration in the interstitial fluid and sending data every few minutes to a phone or handheld device. This technology helps patients adjust their insulin doses precisely, and track their body’s response to each meal or exercise session – something that was previously nearly impossible.

Surprisingly, however, the vast majority of CGM users today do not have diabetes. Thanks to aggressive marketing campaigns by health tech companies and influential individuals, CGMs have become a must-have item for those who are passionate about tracking their personal health down to the last detail, helping them “know themselves better” through blood sugar data after each meal or exercise.

Faced with this situation, medical experts warn of a dangerous trend: Using CGM without clinical indications.

There is little evidence that CGM is helpful for people with normal blood sugar levels, says Jody Dushay, MD, an endocrinologist at Beth Israel Deaconess Medical Center.

A healthy body is very efficient at regulating blood sugar, she explains. Fluctuations in blood sugar after meals are completely normal. The problem is that many people worry too much about these minor fluctuations, which can create a feeling of illness when there is no illness.

The expert also warned that the devices are not always accurate and can sometimes give misleading results, especially if not properly instructed.

Meanwhile, people with no risk factors for diabetes are using monitors simply out of curiosity, said Dr. David Kessler. Having worn a CGM for research while writing his book, Kessler admitted that “it’s an interesting tool to experiment with.”

For people with prediabetes, obesity, or a history of gestational diabetes, CGM can be a useful tool. However, for the rest of us, chasing blood sugar readings when our bodies are functioning normally can lead to unnecessary anxiety and a lifestyle dependent on the numbers, Dr. Dushay said.