How Continuous Glucose Monitors (CGMs) Improve Metabolic and Mental Health

Bret: 
Continuous glucose monitors, or CGMs, have taken the metabolic health world by storm, but not without some controversy. Now, I believe that as a whole, CGMs are an incredible tool for helping people improve their lifestyle and metabolic health. And by improving metabolic health, they have the potential to help improve mental health.

However, there are some caveats and important details to understand to get the most benefits from CGMs. So, let’s dig into the details so you can better understand if CGMs could help you achieve your health goals.

Welcome to the Metabolic Mind Podcast. I’m your host, Dr. Bret Scher. Metabolic Mind is a nonprofit initiative of Baszucki Group where we’re providing information about the intersection of metabolic health and mental health and metabolic therapies such as nutritional ketosis as therapies for mental illness.

Thank you for joining us. Although our podcast is for informational purposes only and we aren’t giving medical advice, we hope you will learn from our content and it will help facilitate discussions with your healthcare providers to see if you could benefit from exploring the connection between metabolic and mental health.

Now, as many may know, a CGM, continuous glucose monitor, is a small device that goes on your abdomen or upper tricep area. It has a microfilament that pierces your skin and sits in what’s called the interstitial space, and it provides near real-time measurement of your blood sugar. So, the first caveat is it isn’t perfect.

It isn’t actually in your blood. So, it’s not directly reading it, and there is a few minute delay in it’s readings between what’s in the blood and what it picks up on. But all in all, they tend to be very close to your blood glucose level and very close to real time. Now, they were first using people with type I diabetes who needed to adjust their insulin pumps quickly, according to their momentary glucose readings.

But others quickly saw the utility for helping people with type II diabetes, metabolic dysfunction, and even people without any medical conditions who want to improve their metabolic health. And since there’s such a strong association between poor metabolic health and the risk for mental disorders like depression, anxiety, bipolar disorder, schizophrenia among others, it makes sense that by association, CGMs can help improve mental health as well.

But here’s the problem with what we’re doing now. So, the blood sugar measurements we usually use in medical practice have some gaping holes in what they tell us about our metabolic health.

Fasting blood sugar is the most commonly used, and in my opinion, most worthless test that we have. It’s a one-time check and tells us nothing about what our blood sugar is doing 99.9% of the time. So, a hemoglobin A1C is much better as it provides an estimated average blood sugar over a three month period, but that requires waiting three months to evaluate the effect of a lifestyle or medication change or other intervention.

And it doesn’t tell you specifics about what you did that may have helped or hurt your blood sugar, but a CGM tells you so much more. You can see your fasting blood sugar, how your blood sugar responds to specific meals, to exercise, poor sleep, stress and more. And it can give you a daily average of your blood sugar. It’s like a running hemoglobin A1C on a day-to-day basis.

So, are you curious about maybe how the heart-healthy oatmeal affects your blood sugar? Or the Honey Nut Cheerios with a heart healthy seal in the box? Many people find they aren’t so healthy after all once you’re wearing a CGM. Or since many in the medical and dietary world believe red meat causes diabetes, maybe you want to see how red meat affects your blood sugar?

Chances are you’ll see red meat within the context of a low carb diet treats rather than causes type two diabetes for most people. And there are other cool experiments you can do, like what happens when you eat fat and protein first and carbs last or vice versa? You’ll likely see a difference in your blood sugar response with the glucose peak lower and slower when carbs are eaten last after fat and protein.

Or how does going on a walk after your meal affect blood sugar? It likely helps blunt the post meal, or postprandial rise. And there are endless experiments with food and other lifestyle activities that you won’t be able to learn with just a fasting blood sugar or even in hemoglobin A1C, but there tends to be disagreement about how to interpret a CGM.

My disclaimer is that there haven’t been outcome studies on healthy individuals using CGMs. Most of the data come from people with type I or some with type II diabetes, but we can use that data as well as data from observational studies in healthy populations to reach some general conclusions. But here’s a key point.

The goal isn’t necessarily a completely flat glucose line, and here’s where CGMs can be controversial. It’s normal to have variations during the day. The key is how high they go, and how long they stay up before returning to baseline. I’ll say that again. It’s normal for glucose to go up and down during the day, but how much up and down is okay or healthy?

Now, we have to admit right, there isn’t clear consensus on this question for people without type II diabetes, but I can say it should be better than the general population. As some studies suggest, over 90% of the American population have some degree of metabolic dysfunction. So, in this setting, we don’t want to be normal or average, right?

So, my opinion is that postprandial blood sugar increases should be under 140 milligrams per deciliter at a maximum and 120 is likely even more ideal. And they should return to baseline within an hour after eating. But being even tighter than that is unlikely to provide significant further benefits. I think, again, there’s no data on this, but to me it just makes sense from the data that exists.

And there are other situations to consider with CGMs. For instance, those who practice intermittent fasting and eat low carb may find their early morning blood sugar rises. Maybe they go from mid 90s to now 105 or 110. According to medical guidelines that come from a high carb society, this is a sign of pre-diabetes and insulin resistance.

But many who are eating low carb or in ketosis may find this finding is consistent with what’s called the dawn phenomenon, and the CGM may show that their average daily glucose is improved from before and solidly in the normal range. Thus, suggesting the morning glucose rise is a normal physiologic response to low carb and intermittent fasting and not a marker of insulin resistance.

But you likely need a CGM to investigate with that granularity if it’s indeed the case. So, situations like this highlight the need to evaluate standard tests within a different lens for those in ketosis, and that’s one of the many reasons why we recommend working with a healthcare practitioner experienced with ketogenic therapy.

There are a number of sites where someone can search for these practitioners, and we’ll link to them in the description below. And one more thing to mention is that CGMs can be a great accountability partner. What I mean by that, let’s say you want to stray from your low carb way of eating and add in high carb or high sugar foods.

If you don’t feel any different right away, there may not be a deterrent to continuing along this path. But if you see your blood sugar shooting up in real time, all of a sudden you may be more likely to get back on track. And that’s a powerful accountability partner. So, the bottom line is that a CGM can be a powerful educational and accountability tool to help someone improve their metabolic health.

And given the connection between metabolic and mental health, they can likely be powerful tools for helping with mental health as well.

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