Can Continuous Glucose Monitors (CGMs) Improve Your Health?

Spikes in glucose, peaks and valleys, and pre-diabetes are health topics we hear about often. How do we avoid the pitfalls associated with elevated glucose levels and how does a continuous glucose monitor help?

Now, more than ever, people want as much personalized health information as they can get. This includes, but is not limited to, heart monitors, sleep monitors, metabolic measurements, and body composition percentages.

Some of these tools can be helpful, and some may be more focused on profiting from those of us who are forever curious!

So how do we know if a glucose monitor, or better yet, a continuous glucose monitor (CGM) can impact our health in a positive way?

Here’s what we discovered after reviewing the research, interviewing Registered Dietitian Lauren Kremer (an expert in the CGM field), and trying the monitor ourselves.

A quick note on blood glucose 
Also known as blood sugar, it’s the body’s main source of energy and comes from digesting complex carbohydrates from the food we eat and breaking them down into smaller sugars absorbed into the bloodstream. When the body calls for more energy, the pancreas releases a hormone, called insulin, to bring sugar from the blood and into the cells. 

Diabetes mellitus is a chronic condition that causes blood sugar to rise when insulin isn’t being produced or utilized in the appropriate ways. CGMs were initially developed so that people with diabetes could have a constant read on blood sugar throughout the day.

CGMs…but without diabetes?
The thought is that analyzing blood sugar patterns  especially after meals or after eating certain foods — give us clues as to how our diet impacts our bodies, regardless of whether or not we have diabetes. Potentially, it gives us an opportunity to make changes in an effort to prevent chronic inflammatory states – such as cardiovascular disease — from developing in the future.

What is so important about blood sugar responses?
We have all seen headlines pinpointing sugar as the cause of inflammation.

But tangible evidence on this is pretty weak. Meaning, one research study may show that, on average, people with diets high in added sugar also have more pro-inflammatory markers in their blood. But this is not direct causation, and it also leaves out any consistencies in what other factors people who eat high added sugar diets may have in common. 

Also consider that this is specific to added sugar, not in those with diets high in fruit. This is a really important point, because as Lauren and I discussed, eating a piece of fruit does cause high blood sugar spikes. Meaning a high blood glucose spike in isolation may not mean much.

How much do CGMs cost?
They are not cheap. Lauren uses ABBOTT freestyle Libre CGM which sells two monitors for $200. (She mentioned that with insurance help, the price sometimes goes down to $60.) And while the price may seem reasonable, each monitor only lasts for two weeks – if it doesn’t fall off during activities or simply when bumped on a corner of the wall. Lauren added that she has worked with many clients over the years, and it happens often.

How are the monitors installed?
Ann volunteered to try one, and the sensor application was pretty straightforward using the instructions. The actual “needle” was so small, Ann said she didn’t even feel it going in. The more challenging, or time-consuming, part was linking the sensor to the app on the phone and making sure the data was being recorded properly.

How do CGMs work?
Once connected, CGMs pull from interstitial fluid. (Interstitial fluid is outside of body cells and blood vessels.) So while this is not measuring actual blood glucose, it’s generally accurate. However, it’s about 15 minutes behind a real-time finger prick or blood draw at the doctor’s office for example. 

This is why some individuals with diabetes prefer a glucometer (which checks actual blood sugar) or an insulin pump with glucometer for accuracy. These devices are sold over the counter and are inexpensive.  

CGMs monitor blood sugar 24/7, but to get the most complete picture, the user must scan the sensor every eight hours to download data onto their phone. Ann mentioned she had a few glitches where the scan failed and she had to try again; or a reading seemed off and she was concerned, but then it would go back to normal range a few minutes later.

Can CGMs interpret your results?
The short answer is no.

This is why Lauren recommends using a CGM in conjunction with a dietitian, as it can be tricky to deduce and understand blood sugar trends. Her clients are asked to write down everything they eat and the time they eat it. Since this level of detail is not easy to document (or document accurately), she actually asks people to take photos of their food and send them to her so that she can better interpret diet recalls. 

This is vital. If there is not an accurate food intake log along with blood sugar results, the data itself won’t be particularly helpful.

Ann was initially concerned when a reading went out of range (as in the red area above) and would refer to Google to see what it could mean. She is well aware this is not a great idea in general, but it’s hard to resist doing so when the blood sugar patterns are confusing!

What can these blood sugar results tell us?
CGMs are especially powerful for people with diabetes and pre-diabetes for several reasons. First, the monitors identify key moments before blood sugar dips too low. They also help determine how certain foods impact blood sugar as well as how the disease is progressing.

More broadly, this tool could provide some clues for those who can’t figure out why they feel certain ways throughout the day – for instance, feeling especially lethargic mid-day or hungry soon after eating a large breakfast. Lauren works like a detective, also helping clients identify various life events, independent of meals, that could impact blood sugar.

For example, clients may wonder, “Why did my glucose spike at 2am when I hadn’t eaten anything in hours?” Lauren says sometimes those anomalies are due to a stressful moment we didn’t even consider, like stress during travel, an unexpected phone call, or a late night argument.

Blood sugar can also be elevated on average due to long-term stress, such as periods of life when caring for a sick relative or prolonged periods of stress during a workday. As Lauren said, think of it more like being in a constant state of fight or flight, which would absolutely impact blood sugar in a more chronic way.

Is this evidenced based?
Lauren is not aware of any peer-reviewed scientific research which provides evidence that CGMs improve overall health; however, she has anecdotally seen people learn about themselves and how their behaviors impact their blood sugar in their own unique ways. She feels this can be a game changer for some of her clients. She has even experimented on herself and made a few changes to her own diet and lifestyle based on the data.

But it’s not for everyone.

Who should not try this?
Lauren does not recommend CGMs for any of her clients with obsessive tendencies, including but not limited to eating disorders. It’s much too triggering. In my opinion, it’s probably pretty triggering for most people, because it’s challenging to absorb this information without feeling the need to omit “offending” foods or turning to restrictive patterns of eating.

In fact, Ann and I were texting throughout the day and night, experimenting with different foods to see what would happen on the monitor. It’s quite time consuming, and we spent much of it trying to decipher why her blood sugar went up or down and whether or not it was related to this or that thing she ate (even if her blood sugar remained in the normal range!). 

For those who are in tune with how they feel after eating and/or don’t want to fall back into patterns of labeling foods as good or bad, save your money – you don’t need a CGM. 

‍♀️Who should try this?
Lauren underscores that along with counseling, lifestyle modifications, sleep adjustments, and medications, real time feedback from CGMs can be transformative for those with prediabetes and even those with diabetes. They can help to identify small but impactful changes to reverse prediabetes or make blood glucose more manageable.

Ann mentioned that some of her results actually reinforced to her that eating the foods she liked — including but not limited to M&Ms, vanilla syrup in her coffee, and ice cream — did not send her glucose soaring. She has never had an issue with glucose control or pre-diabetes, and this helped to reinforce that she didn’t need to worry.

Lauren also mentioned that high performance athletes have been trying the monitors to see how certain pre-race foods impact their ideal blood sugar (and how long after eating that takes), to determine when and what foods will optimize blood sugar at game time. This is a niche audience, but we know that every second counts for some!

Any general recommendations regarding food intake and blood sugar?
Add, don’t subtract!

When we eat carbohydrate-rich foods (anything from fruit, grains, juice, or starchy vegetables for example) without protein or fat at the same meal, blood sugar tends to spike. Lauren says this is the case for most clients.

This reinforces the idea that carbohydrates are not “bad” – even for those with diabetes. But to prevent blood glucose spikes or feeling hungry soon after eating, it is helpful to pair these foods with the other macronutrients, like fat and protein.

This is especially true for a food like oatmeal, for example, which has nutritional benefits such as beta-glucans as well as vitamins and minerals, and of course is yummy! Side by side, plain oatmeal will spike sugar higher than a bowl of ice cream, which Lauren says surprises her clients. But in no way does this mean oatmeal should be avoided. Simply add to it! Pair with nuts or nut butter, Greek yogurt, or alongside an egg it’s not only more filling and sustaining. This combination of macronutrients produces a more muted glucose response.

Lauren also asks clients to test their favorite foods in isolation, just to see what they will do to blood sugar. She says this doesn’t mean people need to avoid them if they don’t like what they see. It just means that eating other foods at the same time, like a handful of nuts, can be the little adjustment they need. Additionally, movement after meals (even something as simple as a 10-minute walk) can help blood glucose levels from becoming too elevated.

Recipe Inspiration
These Fountain Avenue Kitchen recipes are examples of combining oatmeal or fruit with protein and fat which may put a damper on glucose spikes: Oatmeal Packet Mug Muffins, Banana Nut Quinoa Muffins, Green Smoothie Muffins, and No Bake Pumpkin Spice Energy Bites. 

For savory dishes, people may fear pasta, rice or bread. The same advice goes for these carbohydrate foods – when mixed with non-starchy veggies, fat, and protein, they can make for a satisfying meal without a spike in glucose.

For example, add on to a pasta dish with this Roasted Veggie Pesto Pasta (the oil in the pesto is a well-paired fat alongside the fiber from the non-starchy broccoli and mushrooms). Consider some Fiery Grilled Shrimp on the side for added protein. A one-pot dish like Braised Chicken with Rice and Spinach is not only easy and tasty, but this is also a good example of how to balance of carbohydrates, protein, and fat. Top toast with fat and protein for breakfast too to help stay fuller longer like with this Eggs, Lox, and Avocado Toast .

✅ Takeaways – both personal and general
Overall, CGMs feel like another tool most of us (without diabetes) don’t need. It’s another thing that makes us worry about what we are eating, and perhaps in an unnecessary way. Not to mention the expense. This is a business that profits on people using it, so remember that just because it’s labeled as a health tool does not mean it actually is appropriate or helpful for everyone. In fact, the customer should be pretty niche. 

For those with prediabetes trying to manage blood sugar or those who have difficulty identifying why certain foods have an impact on how they feel, CGMs may provide some insight. Some people find this tangible information empowering.

For those who have obsessive tendencies, history of disordered eating, or those trying to stay away from restrictive patterns, I’d leave this trend behind. For those of us (including me!) there’s more risk than there is benefit.

If you have experience with CGMs (either because of diabetes or not), feel free to share your experiences in the comments section below. We love hearing from readers!