Ep.104 Glucose monitors: Do They Work For Teens With Prediabetes?

A friend of mine, who's also a doctor, called me about a patient: a patient she's trying to help reach a healthier weight. Her question was simple. "Should I put them on a glucose monitor? They do not have diabetes, they just want to lose weight".

If you've seen these little sensors all over your feed, you've probably wondered the same thing. So in this episode I give you the honest answer.

Here's what we cover:

1. What a continuous glucose monitor actually measures, and why it's lifesaving for teens with diabetes
2. Why "a screening tool, not a treatment" is the clearest way to think about it for everyone else
3. What the research really says about teens without diabetes
4. The quiet risk of number-watching, and how it can push a teen toward fearing food
5. What actually helps a teen improve insulin sensitivity, without dieting

If you'd like the 3 signs of insulin resistance most parents miss and what to do, grab my free guide.

All the best, 

Dr Jenny

I’m Dr. Jenny Gourgari—pediatric endocrinologist, certified in obesity medicine and a health coach. 
After helping hundreds of teens struggling with their weight and hormones, I’ve created a whole new path by doing what most programs miss: balance puberty hormones naturally and create habits that actually last.

Here's what makes this different:
✅ No dieting. No calorie counting. No shame.
✅ No more food fights between parents and teens.
✅ No weight obsession—just healthy habits
✅ Real science behind how puberty hormones affect weight
✅ A safe, supportive approach that prevents eating disorders

Because when teens understand their hormones and get the right support, they don’t just lose weight—they gain strength, energy, confidence, and freedom!

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Transcript

 Welcome to another episode of the Lifestyle and Weight Loss For Teens podcast. This is Dr. Jenny Gourgari, and on today's episode, I'll be talking about continuous glucose monitorings. So what are continuous glucose monitorings? I recently had one of my friends who's also a doctor, and she had a patient that she was trying to get into a healthier weight and she asked me, "What do you think? Should I put her on a CGM, continuous glucose monitoring?" Because the idea is that if somebody wants to get into a healthy weight and they're watching their blood sugar, they're gonna get into a healthy weight. And so I started looking up the different types that are not really prescribed by doctors, and then I started to get all these ads thrown on my face almost every single day about all those glucose monitorings that exist. It's like one of those popular things that people talk a lot about it, people wear it particularly people that wanna be healthy or they wanna control their pre-diabetes and they wanna get into a healthier date. They wanna get into a healthier weight. So what's really the evidence, right? What has science taught us about whether these gadgets, those continuous glucose monitoring devices, actually work for teenagers that wanna get into a healthier weight? And the- they're widely used for people that have diabetes, and particularly for people that have diabetes that is managed with insulin. And the main reason CGMs were discovered and is because they really have a utility to help people that have diabetes to avoid the risk of hypoglycemia. That's how they started. And what do they actually measure? What do continuous glucose monitors actually monitor? They monitor the amount of sugar not in the blood, but in the fluid that is between the cells in the body, right? So usually we put those CGMs in the arms. We can put them in the stomach. We can put 'em in the upper buttocks. We can put them in the thighs. Really, we put the CGMs in places where there is subcutaneous tissue, there is like a lot of fat. And then with those monitors, we look what is the sugar. So- There's very clear evidence that CGMs are very helpful for people that have diabetes and they take insulin. But for adults and teenagers that use those, not because they have diabetes but because they wanna get into a healthier weight or because they have prediabetes and they wanna reverse their prediabetes, now what is the evidence for these particular people? And I'm gonna tell you that unfortunately we don't have good evidence to suggest that the use of CGMs actually is good and has been proven to improve weight management in people that use them to get into a healthier weight. Now, let me explain. When we say this is a tool, right? It is a tool. Basically, when you eat sugar, you're gonna see that the sugar goes, when it goes high on your blood, that's like normal, and when you don't eat, it's gonna be lower, right? It's not gonna be a spike. Ri- that really is what it's telling you. So the idea behind it is that if people could see how high the sugar would go, then that would make them eat less, and that would make them avoid to have sugary things. So- Let me tell you that the studies, again, we don't have a lot of studies, but the few studies that were done in teenagers that had that were overweight and they used CGM, they didn't really find evidence that alone was enough to make them lose weight. The continuous glucose monitoring was not enough to help them change the average glucose, whether they could see the numbers or whether they could not see the numbers. But again, I have to say those studies were not the best in the sense that they were, like, only a few teenagers, like maybe 50 to 100 or something like that in different, among the different studies. And they were not long term. And the- my question, like if I had to do that research would be will it help whether this is used in a program that not only targets the sugar, but is a total lifestyle modification program when you have actually feedback, when you have someone looking at your values, when you have someone discussing with you what happens when you have those spikes, and when you do an intervention and then you see how it was and how it went. So my personal opinion, and I may be wrong, is that those tools could be helpful as a tool, as like a, as a tool in a li- in, in a on top of or within another program that not only targets sugar, but it targets the whole behavioral modification system, right? So- we, w- you know, if you tell someone, "Here's that. Wear it. Come back after a week. Let's see what happens." And then you look at it, and then you see, oh, what happened that day? What happened that day? What if you didn't do this day? What if you do that day? That is different than if you just have someone eating and looking at it, and nobody cares. S- eating, looking at it. So what? I eat that, I see it. The self-regulation is basically is not as strong in my opinion, as if you have someone else looking and intervening and discussing what you're gonna do about it. Again, the research though, the actual research so far in in, in 2026, the data that I am aware of, they have not shown that just by wearing CGMs teenagers can improve their weight, or even adults can improve their weight. Like the data in adults show that there can be behavioral like the adults are more likely to change their behavior on what they eat than when, than teenagers. However, the data in adults about losing weight, as far as I know, if they're not doing anything else, all they do is CGM, I don't think they're good. But my focus is really the teenagers. And, I know that for teenagers that is not true. Another point on the use of continuous glucose monitors used to be that they were only for teenagers that have diabetes and they were medically indicated. They still are medically indicated. We prescribe, I do this all the time for my patients that have d- diabetes. But for people that don't have diabetes, insurance is not covering, it's an out-of-pocket expense. Now, how much does it cost? There are different types of CGMs available. Some are cheaper, some are more expensive. And, the cost can add up, maybe $50 per month $300 per month, depending on the frequency and the type and all those things. So the question is this cost justified, right? Are you making this expense, you're putting that money, do you get the benefit that you expect? Are you putting the best effort, or are you just wearing it because it's cool or it's trendy or I don't know what? You can always do that if you don't care. Fine. But th- when we are evaluating a tool, whether it is justified use is there risk and benefit? You have to weight those two. What is the risk versus the benefit? And the other thing is that we don't have very good data on is this constant thinking about what is my sugar, did it increase? Or I ate banana and it went up, or I should not eat banana, or I ate pasta, I should not eat banana. This hyperfocus 24/7 on the sugar level, is that leading to any kind of abnormal behavior? Is it possible that it may lead to distorted eating behaviors when it's not supervised by somebody? And how- what is the effect that it has in teenagers that are particularly vulnerable in eating disorders? Again, we don't have data that says the use of CGM is linked to eating disorders as far as I know. But it's just a thought that I have and a question that I would like someone- would like an answer someday. Because if there are data that show that instead of, like we know it doesn't lose weight by, they cannot lose weight by itself. But if it ca- if it actually leads to e- distorted eating behaviors, then not only does it help, but it can do harm, right? So again, it is a tool and like any other tool, like when you use it, you can have both negative and positive effects. We have to be like very careful. So again, I am, again, I'm not against CGMs. I definitely use them with parent, with teenagers that have diabetes. And I'm flexible with teenagers that have pre-diabetes and they just wanna pay for it and just use it. If they feel that gives them more awareness and if that data is under some supervision from a health coach where they're looking the data and that has a benefit on them, I'm like, "Sure, do it." But if you're just doing this without any other modification I think it's very unlikely you're gonna get any meaningful results just by wearing the CGM and doing nothing else. And the other thing I would like to mention about the use of CGMs is that it is normal to see high numbers and low numbers when you're eating something, right? That's normal physiology. We don't know about it because we don't wear CGMs in our daily routine. But let's say if you eat a banana you're gonna see that your sugar goes high. That's normal physiology. And if you eat a piece of chicken, then you'll see that your sugar does not go up because sugar has no carbs, banana has more carbs. So what is it that determines this change in behavior when you see these variations in the sugar? Are you going to look that after you had a glass of milk, the sugar go- went high, and then you're gonna say, "Oh, I'm not gonna have milk anymore. I'm not gonna have banana anymore because that increases my sugar"? Really it takes, and it's like how much did the sugar increase? Now, we know that your blood sugar after two hours of carbohydrate meal should not be more than 140. 140 to 200 is really pre-diabetes. Above 200 is diabetes, right? So looking at those data and evaluating that data, what they mean, that's where you need the guidance from somebody who knows what they're doing. Because it can be tricky if you're just looking yourself and you don't know much about the normal variation of the sugar versus the abnormal variation of the sugar, and then that may lead you to avoid eating all carbs altogether. And particularly for teenagers, then they can get into a keto diet if they're doing that, which we know is not the best, which we know leads to abnormal eating patterns, which we know does not allow has risks for growth and bone development in teenagers. And you can go and listen to a previous episode where I talked about keto diets in teens. But my point is, if you're using CGMs, if teenagers particularly are using continuous glucose monitors, how are they interpreting the data? What does that data tell them to do? And what they're actually doing, is it healthier or is it not healthier? Because it can be healthier if you avoid the cake, but it can also be not so healthy if it makes you avoid eating the banana. So those are just some thoughts that I wanted to share. And again use of continuous glucose monitors in teenagers with pre-diabetes or insulin resistance is not very clear. The science is not very clear that there is a clear benefit. The benefit is definitely clear for those that have diabetes. But if it's not diabetes yet, I would recommend that you work with someone else, not just wearing the continuous glucose monitoring. If you like that, hit subscribe if you're watching on YouTube, and follow my podcast so that you never miss a future episode. Take care. I'll talk to you soon.