The Extra Scoop: The Truth About Glucose Monitors

0:00At Sierra, discover top workout gear at incredible prices, which might lead to another discovery. Your headphones haven't been connected this whole time. Awkward. Discover top brands at unexpectedly low prices. Sierra, let's get moving. Race the rudders. Race the sails. Race the sails. Captain, an unidentified ship is approaching. Over. Roger. Wait, is that an enterprise sails solution? Reach sales professionals, not professional sailors. With LinkedIn ads, you can target the right people by industry, job title, and more. Start converting your B2B audience today. Spend$250 on your first campaign and get a free$250 credit for the next one.

0:40Get started today at linkedin.com slash campaign. Terms and conditions apply.

0:48Welcome to The Extra Scoop, our expert-led bonus episodes, giving you the need to know on the topics everybody is talking about. That's right. From gut health to sleep, hormones to skin, we are cutting through the noise with top experts, so there is no fluff, just facts. Exactly. It's all quick, practical, evidence-based advice to fit into your busy lives. So this is The Extra Scoop. Let's get started.

1:17As our listeners may know, our Extra Scoop episodes are all about taking those topics that everybody is talking about and quickly breaking them down for you so that you have expert-led insights that leave you informed and empowered when it comes to your wellbeing. Now, this week, we are talking about something that has absolutely exploded in the wellness space recently, and it's the use of continuous glucose monitors or CGMs, as we'll probably refer to them today. And I attended a wonderful talk a few weeks ago where I saw our expert speaker today. So to help us unpack the facts, we're joined by the wonderful Dr.

1:54Javier Gonzalez, the Professor of Nutrition and Metabolism at the University of Bath. Now, Javier recently co-authored a super interesting study that looked into how CGMs impact non-diabetic adults. So remember, these are targeted at the entire population at the moment, it seems, even though they were obviously invented for diabetics. And he found that they may actually be giving misleading results and potentially encouraging, well, encouraging unhelpful dietary choices and shifting how people view their health. so we're so excited to have him on the extra scoop to share the insights and help us make some sense of it so thank you Javier.

2:34Thank you for having me yeah delighted to be on the podcast today. Can we start at the top if you don't mind Javier because I'm sure pretty much anyone listening has heard the term blood sugar has seen someone talking about a blood sugar monitor or seen someone wearing them but I think it would be very helpful just to get a 101 what are we talking about with blood sugar? Why does it matter? And what are these glucose monitors? Yeah, I think it's a great place to start. So our blood sugar is blood glucose concentration. So the main form in which the sugar circulates in our blood is in the form glucose.

3:09And it's a really important fuel for many of our body cells, and in particular, our brain. So our brain is a major consumer of glucose. And that's partly why it's so important to measure the level of sugar in the blood for people with diabetes because they need to keep their glucose sufficiently high that the brain has enough fuel. If that goes too low, then that can be very dangerous indeed. People can enter into a coma, for example, if the brain isn't getting enough fuel from sugar. On the flip side, if we've got too high blood sugar levels, then that can cause damage in the long term. If we've consistently got high levels of blood sugar, that can damage things like the blood vessels around our eyes that can lead to things like blindness.

3:55It can damage the blood vessels around our kidneys and cause kidney disease. And it can damage the large blood vessels and lead to cardiovascular disease or heart disease. So we want to keep our level of sugar in the blood within a healthy range. And for most people, that's not a problem. We don't really have to think about it. But for people with diabetes, of course, that's the main challenger of their condition. And these monitors were developed to help people with diabetes better manage the levels of sugar in their bloods, because previously, people would have to perform these finger prick tests where they'd pierce their skin on their finger and take a small drop of blood and measure the concentration of sugar in that blood droplet.

4:37That's, of course, just annoying to have to do to keep having to pierce the skin there. And so these monitors have made great advances for people with diabetes. But it's important to remember that they're not measuring in the blood itself. So what we want to know is the amount of glucose that's in the bloodstream, that our brain is going to be exposed to, that our other tissues are going to be exposed to. But the way these devices work is they measure glucose in something called interstitial fluid. And that's the fluid that bathes our cells. It's not directly in the bloodstream. And so there's one level of difference there between what's circulating in the blood and what these devices are measuring.

5:18And so they try to correct that by using algorithms that are proprietary. So we don't really know exactly what the companies are using in their equations here, but they use these algorithms to try and estimate what the true blood sugar level is. And that's really challenging to do for two main reasons. One is there's a time lag between what's going on in our bloodstream and what's going on in the interstitial fluid. Also, just the absolute number differs as well. The concentrations we get differ. Those two differences are mainly why these devices aren't perfectly reflecting what's going in the bloodstream.

5:54Now, the degree to which we get this difference then really depends on what you're using them for. For example, for someone with diabetes, they might have big swings in the range of glucose that they see, And so a small difference in the measurement error doesn't make so much of a difference to the way they use the monitors because they're dealing with very large fluctuations in blood glucose. Whereas for people who don't have diabetes, we keep our blood sugar levels within a very narrow range anyway. And so small measurement errors make a bigger difference to how we might interpret the values that we get.

6:30I mean, you've summarized it so perfectly there. So it helps our listeners understand it really isn't black and white. It's not on 100 % accurate reading. if you put a CGM on your arm or wherever you're placing this, you're most definitely not going to get a number that reflects what's happening in that exact moment in your bloodstream. Is that what you're trying to say as well? Exactly. Yeah. So no device is going to be perfect, but the degree of the imperfection that is relevant really then depends on the person and the use that we're trying to apply these monitors to. And then if we have a think about the fact these are used in programs, weight loss programs.

7:07They're used in a variety of different ways right now. You obviously worked on a paper with Bath University. Shout out to Bath, by the way, because I grew up near Bath in a town called Malksham and I used to go to Bath every weekend and I've done one lecture at Bath Uni. I did a visiting lecture a few years ago. So love it there. And the research you did, it was kind of like a sigh of relief for the scientific community because we've been seeing these links between blood sugar and weight loss. There have been explosions of popular social media accounts talking about glucose all the time. Could you just delve in a little bit and explain why you think these CGMs have been placed in weight loss programs to start with?

7:50I think one of the reasons is the idea that a food that might be healthy for some reasons. For example, foods that might be slowly digested and absorbed and release the carbohydrates slowly into the circulation should produce a lower blood glucose response to that meal. I think people then maybe oversimplify it by thinking that if a food is healthy for one reason, such as reducing our blood sugar levels, it must also be healthy for all other reasons, including things like weight loss, when weight loss can be completely separated from our blood glucose concentrations. Can I ask a question on that?

8:31I don't want to be reductive in my question, but it feels like listening to you speak on this, certainly where Rhi and I sit and a lot of the conversations that we have, a lot of the reason this show exists is we feel like the conversation around health and wellness has become very reductive, very sensationalist and has steered us quite a long way from the foundations and the kind of basics of health, a balanced diet, going for walks, managing your stress, the boring stuff essentially. And when I listen to you talk, the thing that I take from it is that it feels like this is very symptomatic of this desire that we have at the moment for kind of continuous self-optimization.

9:11You know, I eat a balanced diet, but let me put on a monitor so I can make it perfect. Let me try and be perfect. And in the pursuit of perfection, A, it's a highly stressful, but you're saying it's not even accurate. So you're stressing yourself out and then you're having inaccuracy. And to your point as well, like for most people who are eating a healthy diet, that healthy diet or healthy-ish diet keeps their diet naturally and their blood sugar in the healthy range. So they don't even need to be thinking about this. So to me, it feels like what we're talking about here is highly symptomatic of an industry that has become quite reductive where, to your point, one thing equals all else.

9:49A healthy diet means it must be weight loss, it must be X, it must be Y. It's becoming this highly reductive way to talk about what is so complicated in terms of nutrition, food, science. Absolutely. Obviously, I'm speaking as a scientist who ends up studying things with a bit of a reductive way, but then the way I live my life isn't that way. I think that's the way people should try to view things. I think one of the best phrases that might summarize part of the point you're making there is we can do things imperfectly right or perfectly wrong in the sense of these devices are helping us maybe achieve that perfection.

10:25But if they're not measuring things with the perfection of accuracy, then we're getting it wrong. And there's also another element to this, which is the focus on a single metric. So one of the problems with solely focusing on glucose as the only health outcome is it can lead to dietary choices which have other negative health effects. And probably the easiest example of this to think of is the easiest way to keep someone's glucose perfectly flat would be to avoid all carbohydrates. So to go on a very low carbohydrate diet, which might happen to be high and saturated fat. We and others have done similar kind of studies where we do this.

11:09And in those scenarios, people's LDL cholesterol, the cholesterol that causes cardiovascular disease, tends to increase. So they might be seeing their blood sugar being perfectly flat and thinking, this diet is very, very healthy. But other things under the bonnet that they're not measuring could be actually causing harm. And so the reductionist simplified view of only focusing on one metric has other potential downsides as well. Absolutely. This is just it. You cannot measure health in one single way. There's a lot going on that you can't see that's happening. Could you break down the findings from your research?

11:44Because I remember you also spoke about the variability when you eat the same food at different points each week with the readings. It was absolutely fascinating. I guess it may even be worth mentioning there were two studies that came out in the same journal within a couple of weeks of each other. There's ours and there's another one that did a similar thing comparing two different CGMs. The previous paper found very big differences in how the CGMs would rank order different foods. If we're talking about foods that might lead to the highest blood sugar response versus those that lead to the lowest blood sugar response, depending on the device you use, you would get very different answers.

12:21And then what our study did was, in addition to having a CGM, we had the kind of criterion method of using the finger stick sampling. So that's kind of using that as the reference method. And we used a system known as the glycemic index testing system to classify the foods that we tested. So what that does is it uses pure glucose as a reference. So people drink 50 grams of pure glucose and we measure the blood glucose response to that ingestion of pure glucose. And that gives us a value of 100. If we then have a food that raises our blood sugar level to just half that of the pure glucose, then that's 50 % and we assign that a value of 50.

13:07And you can use that to give all different foods a different number in terms of their glycemic index. So if they have a glycemic index of 100, they raise blood sugar levels to a very high level to the same extent as glucose. If they're low glycemic index, then they tend to be below 50 or so. What we found is that compared to the fingerprint sampling, the gold standard or reference method, the CGM tended to overestimate blood glucose levels on average, but it also seemed to misclassify the glycemic index of several different foods. So not only is it just off in an absolute sense, it seems to be proportionally off for certain foods and not others leading to this misclassification.

13:51And that was in a non-diabetic community, the research, of course. That's right. Yeah. So to anybody listening, this is still a very helpful device for type 1 diabetic or anybody that, you know, this can really be fantastic for them because the variability can be so high. But for most of us, it's just wildly inaccurate. it. I should also emphasize that we have used these CGMs with great effect in some of our studies in non-diabetic populations, but more to capture overall dietary patterns rather than specifically classifying different foods. What I don't think these devices have the precision to do is to be able to say, for me, this banana is going to raise my blood sugar more than another meal.

14:34I think that's the degree of precision that they lack, they don't have. But just is my general diet leading to a very high or a very low blood glucose concentration? I think that's where they can be still useful. That's a really helpful differentiation where potentially for people who are generally struggling with their health, potentially they're struggling with their weight and they're in the pre-diabetic range or something that to your point, you could use it to get an overall sense of a picture over a period of time that could be helpful in making kind of much larger changes and improving your health.

15:11But for people who are the worried well, essentially, if we kind of be transparent about it, who generally eat quite well and who are generally well, it feels like it becomes kind of an unnecessary stress and one-dimensional view of looking at their health. I think one of the things that I'm very conscious of though, is that these graphs are really visually appealing. You know, there's a lot on social media where you see, if you have a smoothie, it will do this to you. If you have a, and I'm talking about therefore like vaguely healthy things, you know, a banana on its own to your point, it will do this.

15:47And it all makes it look quite terrifying. And I worry that it's creating a kind of a real fear of food. And I was just curious what your take is on that. I agree. I think certainly the visuals are very emotionally impactful. And I do wonder if we can harness that for good. I agree that I think at the moment it probably leads to a negative perception of foods. But I wish we could harness that emotional response to get people interested in nutrition and interested in the science. And at the moment, we're not doing that effectively. And I'll probably add actually that the peaks that you see after the ingestion of meals there, the big spikes, look scary.

16:30But that's one of the other things we explored in this study was if you just take that peak, that's in particular where these devices seem to overestimate things. So they overestimate the time that people spend in this high blood glucose range by more than twofold and up to kind of three to fourfold. So they're overestimating it and giving a greater perception of danger than probably truly exists, again, with the caveats of within this population and within the meals that we tested. And of course, every graph you see. So I think I know the particular ones Ella's discussing on social media. They were just one individual showcasing their own response to food.

17:09I mean, everybody's response is going to be slightly different. And didn't you say you have to test something, wasn't that up to 70 times to get an overall average that you could potentially view as valid? Yeah, exactly. And that's because we do differ between one another, but we also differ to ourselves yesterday. So if you want to know how we respond individually to a certain diet or food, we still need to replicate that multiple times within ourselves to get a true picture. So yeah, these aren't easy to do. And the way in which you see some of the social media experiments take place seem to be overly confident is one way I put it.

17:47It is overly confident. And I'd love to have your view because I don't think we can deny that health tech is going anywhere. Health tech is probably the future and there's pros to it. Of course, it can make access to health care more accessible for so many people on a broader level, potentially could help reduce NHS times. I don't know. There's a lot of talk from these different health tech apps at the moment. There's a lot of them in existence. But what is your overview? Do you think we're ready for personalized nutrition? Do you think we're at a point where, or are we kind of using the car as we're building it or whatever that saying is?

18:22Yeah, I think we're probably not there yet. I think the technology is a great tool to have and to help on the path towards personalized nutrition. But I think we also need to improve study design as well. I would like to think in 10 years' time, we might be closer, but we need all of these things to improve at the same time. So it's study design. It's actually how we analyze the data we get, the huge data sets, and the technology itself. And I'm definitely keen to try to improve the values we can get from these devices and others. And hopefully some of the work, the current work we've published and the work we're doing at the moment can help us understand why we see these differences in people who don't have diabetes.

19:09If we can understand the physiology behind that, we can improve algorithms and measurement methods going forward and hopefully solve this problem. And if people are listening to this, they're probably thinking, maybe I don't need to sign up for one of these at the moment. And to your point, potentially in the future, it could be a really helpful part of a kind of total picture of personalized health. But as it stands, it's probably for lots of people, not necessarily the best use of their time and money at the moment. If people are, though, thinking about, OK, looking at my diet, what are the best couple of interventions or steps I can take to just support keeping my blood sugar for the most part in that healthy range?

19:51Have you got any words of wisdom? Yeah. I hope it doesn't sound boring, but the general recommendation to eat a higher fiber diet is one way to keep your blood sugar under better control. Another one is to select those low glycemic index foods. There are databases available online where the degree to which different foods raise blood glucose levels on average has been reported in peer-reviewed studies. Glycemicindex.com, I think, is the website where you can just search those databases And this also relates to the last question, actually, where I think the benefits we would get from precision or personalized nutrition over and above these generic recommendations is probably very marginal anyway.

20:35So even if we could do it right now, it's questionable the extra benefit we would get over the general advice to eat a diet rich in fruit and vegetables, generally higher in fiber and lower glycemic index, your kind of complex carbohydrates as foods. It's really helpful advice. So anyone can go and look that up. And also, I remember you mentioning about cycling. So you're an avid cyclist, is that correct? Yeah, although I say less so now. I'm running more recently due to lack of time, but yeah, certainly was a cyclist and have worked in pro cycling. And you mentioned looking at nutrition, of course, for athletes, as we know, it's a different ballgame to public health nutrition advice, but perhaps that's an area where these CGMs could be helpful?

21:19Yeah, they can certainly be helpful in training, for example. They're currently not permitted in competition. One of the ways in which they could be useful, for example, is when athletes do very high intensity exercise, that causes our liver to release glucose into the circulation to provide extra fuel for the muscle. If your liver is depleted of its carbohydrate store, then it's not able to do that as effectively. And so with careful testing, you can get some crude measurements of what might be going on in with the physiology of an athlete by using these monitors alongside specific types of training.

22:01Yeah. I mean, watch this space, Olympics in 10 years, maybe everyone's going to be using CGMs and it's going to be gone from our public health health tech. Who knows? Yeah, possibly. Well, this has been so helpful. Thank you so much. I feel like that's given people such a thorough understanding. And I think our big aim is trying to kind of simplify all the noise for people in terms of what do they actually need to do. And I loved that your answer to the question in terms of people's diet that you started it was saying, I know this is quite boring, because it's just what we come back to time and time again, it's like the fundamentals for people's long-term health and wellness is quite boring and it's much more fun to track stuff and it's much more fun to get graphs and it's much more fun to kind of put things in camps of good and bad because it's just a lot more interesting to some extent and clickbaity than it is to say well try and get more fiber in your diet it's also a financial gain ella like think of the financial gain in the wellness industry to showcase these things as being exciting and savvy like they must you know they rake in a fortune.

23:04But also in such a complex industry I think it's really tempting and I totally understand why people want to try this because to have something to tell you what to do I think is a very human approach you know as I said it's such a complicated industry and it's so nuanced and there's so much noise and so the idea that this single thing can tell you essentially like what's good and what's bad and you can live by that is a very appealing concept So I'm not surprised that it's had so much hype. I think it's just important to see that it's not necessarily there to be such a marker and to live by at the moment.

23:39And they're very, very expensive. Would you say, Javier, it's behavior change as well? So it just helps enforce a behavior change to have a visual on what's going on? Yeah, I think it's a really useful tool to engage people in a behavior change. But that's where the support of a dietician or healthcare professional to really ensure that that change is a beneficial one is crucial. So any type of impactful measurement, and this is where these are the epitome of that, because in real time you can see what's going on in your interstitial fluid or blood, then that's the power that it has. But it's really how we can use that to benefit, really.

24:17So to round up, just to reiterate to our listeners, you don't need to be scared of glucose spikes. No. So certainly within that healthy range, there's not really any good evidence that they cause long-term harm. So yeah, if you see a small spike after a meal, that's perfectly normal. So validating, so helpful. Thank you so much for your time today. We so, so appreciate it. Thank you for having me. thank you guys so much for listening to us on the extra scoop we are a community-based podcast we want this to be helpful for you so any requests we want to hear it absolutely let us know which experts that you went on the extra scoop and we will see you on monday can't wait

25:39Liberty Mutual. It's okay not to be perfect with finances. Experian is your big financial friend and here to help. Did you know you can get matched with credit cards on the app? Some cards are labeled no ding decline, which means if you're not approved, they won't hurt your credit scores. Download the Experian app for free today. Applying for no ding decline cards won't hurt your credit scores if you aren't initially approved. Initial approval will result in a hard inquiry, which may impact your credit scores. No one knows your business better than you. So who better to create your website than, well, you?

26:20Wix's website builder puts it all in your hands. Create a beautiful website just by talking with AI or choosing from thousands of templates. Customize every detail with simple drag-and-drop tools and get everything you need to start running business your way. Build more, think bigger, and do it all yourself on Wix. Go to Wix.com.