However, that’s not the messaging or target audience of the aforementioned CGM ads that popped up in my feed, which suggest that pretty much anybody who wants to lose weight or feel better or improve their health would benefit from a CGM. Plus, it’s important to note that people with lower incomes are at a greater risk for prediabetes and type 2 diabetes—not those who can afford to buy CGMs out of pocket.
But when it comes to the general public, experts aren’t convinced that CGMs are necessary.
Currently, there is “no compelling evidence” to say that people without diabetes or prediabetes would benefit from a CGM, Christine Byrne, MPH, RD, a Raleigh-based dietitian who specializes in eating disorders, tells SELF. In fact, one 2019 study published in the Journal of Clinical Endocrinology and Metabolism, in which researchers analyzed CGM data from 153 people without diabetes, found that 96% of the readings were in the normal range.
The non-diabetic CGM market thrives on an assumption underlying a lot of wellness and biohacker culture today: More data about our bodies is inherently better. But that’s not necessarily true, Byrne points out. For starters, CGMs aren’t always accurate, because there’s often a time lag of 10 to 15 minutes and a 10- or 20-point difference between what your CGM says and your actual blood glucose level. And they tend to over-read lows, in particular, Dr. McGill says, which some people may find “disconcerting.”
Blood sugar is also a complex, multifactorial phenomenon. To make sense of your CGM data, you’d ideally be tracking “food, exercise, sleep, stress levels and how your energy fluctuates throughout the day, in order to better understand how these different components affect blood sugar,” Yasi Ansari, RDN, a spokesperson for the Academy of Nutrition and Dietetics, tells SELF. In other words, just because your blood sugar rises 20 points after you eat a mango doesn’t mean mangoes are bad for your health (or even that a mango would have that same exact effect on your blood sugar on a different day).
There are also potential mental-health downsides.
Even if there was enough research supporting the idea that CGMs have a positive effect on your blood sugar, in reality they may also have unintended negative consequences beyond your physical health. For one, fixating on your blood sugar “could cause you to pathologize completely normal glucose responses and fluctuations,” Byrne says. “If you eat carbs, your blood glucose will go up, and that’s totally normal and fine.”
And hyper-focusing on your blood sugar in order to inform your eating choices could also result in greater rigidity around food—especially in people with a history of restrictive dieting or disordered eating behaviors. “Similar to the effect that activity trackers or calorie counting apps can have, using this device may take away from the joy and pleasure of eating, as well as listening to your body when it comes to making food and exercise choices,” Ansari explains. You want to be able to eat and “not always be worried about the impact it might have on blood sugars,” as she puts it.
And there are often easier (more affordable) ways to address many of the issues you hope to resolve with a CGM.
If you’re concerned about or at risk for prediabetes or diabetes, talk to your doctor about getting screened, Byrne says. You can also start with basic, evidence-based measures for stabilizing blood sugar levels, like more physical activity.