The Peter Attia Drive - #165 - AMA #24: Deep dive into blood glucose: why it matters, important metrics to track, and superior insights from a CGM

Episode Date: June 14, 2021

In this “Ask Me Anything” (AMA) episode, Peter and Bob dive deep into blood glucose and why it matters so much with respect to metabolic health and longevity. They explain the need to pay close attention to metrics like average blood glucose, glucose variability, and peak glucose numbers. Additionally, Peter explains why he encourages all his patients, even nondiabetics, to utilize a continuous glucose monitor (CGM) which gives important insights that traditional lab testing and metrics consistently miss. If you’re not a subscriber and listening on a podcast player, you’ll only be able to hear a preview of the AMA. If you’re a subscriber, you can now listen to this full episode on your private RSS feed or on our website at the AMA #24 show notes page. If you are not a subscriber, you can learn more about the subscriber benefits here.   We discuss: The problem with traditional blood tests and metrics for determining metabolic health [1:10]; The superior insights from a continuous glucose monitor [6:15]; Why lower is better than higher: average glucose, glucose variability, and glucose peaks [12:00]; Deep dive into average blood glucose and the importance of having the lowest average blood glucose possible [14:45]; Deep dive into glucose variability and why less variability is better [33:15]; Example of how HbA1c and traditional measures could catch metabolic issues too late [41:45]; Postprandial dips in blood glucose as a predictor of subsequent hunger and energy intake [43:00]; Exploring the idea that the suppression of fatty acids is actually causing hunger rather than a low blood glucose [49:45]; Deep dive into peak glucose and why lower peaks is better [57:15]; What the best rodent models tell us about the impact of peak glucose levels [1:06:25]; Why Peter encourages all his patients to wear a CGM [1:14:30]; and More. Learn more: https://peterattiamd.com/ Show notes page for this episode: https://peterattiamd.com/ama24/  Subscribe to receive exclusive subscriber-only content: https://peterattiamd.com/subscribe/ Sign up to receive Peter's email newsletter: https://peterattiamd.com/newsletter/ Connect with Peter on Facebook | Twitter | Instagram.

Hey everyone, welcome to a sneak peek, ask me anything, or AMA episode of the Drive Podcast. I'm your host, Peter Atia. At the end of this short episode, I'll explain how you can access the AMA episodes in full, along with a ton of other membership benefits we've created. Or you can learn more now by going to PeterittiaMD.com forward slash subscribe. So without further delay, here's today's sneak peek of the Ask Me Anything episode. Hey everyone, welcome to AMA number 24. In this episode, I am joined as usual by Bob Kaplan, and we devote the entire episode to a series of questions that focus around glucose, homeostasis. We send out the discussion basically around the idea of why one would wear a CGM,

especially someone who does not have type 2 diabetes or type 1 diabetes, and we get into the really deep nitty gritty around what is it about glucose that matters so much with respect to health? Why is it that I make such a stink about having lower average blood glucose, fewer peaks of glucose, less glucose variability, and all of the associated things that go with it? So I hope you'll check out AMA number 24 and without further delay, here it is. Oh! Oh! Oh!

Oh! Oh! Oh! Hello, Peter. Hey, Bob. How's it going? It's going well, man. Ready for an AMA?

Ready as always. All right, so in this case, we got great questions about glucose. And we aggregate a bunch. I think it'll be good to do a deep dive. I'm going to go through a couple of questions here, see what you think. So the first question is more of a statement than a question.

I've heard Peter talk about how fast and glucose and even HBA1C measurements can often be misleading. And how he favors OGTT, which is short for original gangster time trial? That's right. Yeah. Okay, perfect. I think it might be oral glucose tolerance test with insulin measurements and also wearing a CGM to get a better sense of glucose homeostasis.

My understanding is that OGTTs and CGMs are typically reserved for people with diabetes. So he's got the following questions. Why does Peter find these tests useful in quote unquote healthy people? What is Peter looking for when assessing someone's glucose levels? What does he like and hate to see? How does Peter define normal versus abnormal control

of glucose? If I'm not diabetic, do I have anything to worry about here? And there's another question that was, are you able to do a breakdown of what you look for on different people's CGM data and what you would advise to improve their numbers? Similar to the AMA you did on lab tests. All right, so I'm going to pause you right there, Bob, and I want you to answer this question for me, honestly. Did you pay this person to ask these questions? Asking for a friend.

I mean, seriously, these are the perfect questions, the most salient questions, the most important questions. And this might become, by extension, then one of the most important AM. And this might become, by extension, then one of the most important AMAs we do, in terms of the aggregate impact it could have on health and longevity. Because these questions really get at the root of where I think, I hate to use this term,

but for a lack of a better word, where the mainstream medical system is just so out of sync with what I believe the future of medicine is going to be. So let's take a step back on all of this for a second. Type II diabetes has a definition, and it is defined as having a hemoglobin A1C concentration greater than 6.5%. And that corresponds to an average blood glucose God, I should know this, but the fact that I

pay so little attention to it tells you why I don't even know it. I believe it corresponds to an average blood glucose of approximately 130 milligrams per deciliter. And of course the way it works is it measures the concentration of glycosylated hemoglobin. So it's taking out red blood cells and it's looking at how much glucose is stuck to them. And obviously the more glucose that is stuck to them, the more you can infer that the average concentration of glucose is higher during the period of a red blood cells life.

But of course this is potentially misleading because if a red blood cell has a very short life, for example, see this in a couple of my patients, including a patient who's recovering from prostate cancer, who still has some GI bleeding issues, patients with gastritis, etc., but women with a heavy menstrual period. So people who are losing significant amounts of blood have a higher turnover red blood cells, they're gonna have an artificially low hemoglobin A1C.

Conversely, people who have red blood cells that stick around a very long time, people with a microcytic pattern, meaning they have very small red blood cells that are less likely to get chewed up in the splenic system, which is where we ultimately break down red blood cells. They're going to have an artificially elevated hemoglobin A1C because their red blood cells are living longer on average than the typical person, which is about 90 days. So that's one reason why

I'm not a huge fan of hemoglobin A1C. But the broader point here is that I find it unhelpful to simply say, if you're hemoglobin A1C is above 6.5 and you have type 2 diabetes, you have quote-unquote a disease. If it is below 6.5, you are normal. Or even if we go one step further and say, well, there's a pre-diabetes, which is defined as 5.7 to 6.4. And those people we have to watch out for, but anybody at 5.6 and down is completely normal. As though there's some enormous difference between 5.6 and 5.7 or 6.4 and 6.5. So, while on the one hand I understand the need to simplify things, I think oversimplification is erroneous, and I think we should view these as a continuum. So glucose at the average level is a continuum. And as the person who asked the question noted,

I am a far greater proponent of CGM. Now Bob, I don't know if you're wondering what this thing on my arm is. But in case you are, this is a CGM. This is a continuous glucose monitor. And as its name suggests, it measures glucose continuously. And while I do not have diabetes, and while most of my patients don't have diabetes, many of them along with I wear this device. And I think what we'll get into today is the why. So what are the metrics we're tracking here and what are we describing as ideal and optimal as opposed to acceptable along those metrics? Anything else I can say broad strokes before we jump into the nuts and bolts of this Bob? No, I think that covers it. I had a question about the continuous glucose monitor. One way if it's like streaming or does it actually take measurements

every certain period of time? Yeah, so actually I thought it would be helpful Bob to just sort of show you and obviously listeners kind of what this looks like So it connects to your phone and every five minutes it is spitting out a number if you look at it in a 24-hour fashion when you turn your phone on your side you get sort of a 24-hour when you turn your phone on your side, you get sort of the 24 hour tracing. So for my last 24 hours, I've averaged about 90 milligrams per deciliter, and my variability has been about nine or 10 milligrams per deciliter or my standard deviation. My peak level has been, let me see, I have to go back and look.

My peak was 102. And by extension, then I've had no peaks above 140. That's going to come up later on. So obviously if my peak was 102 I was never above 140 and my native was 77. So range of 77 to 102. So anyway, that's the kind of data you get out of these things. And obviously they have reports that will spit out your average blood glucose over one day, seven day, 14 days, 30 days, 60 days, 90 days, et cetera, along with the standard

deviation and things like that. And the way these things work, of course, is they're not actually measuring in the blood, they're measuring in the interstitial fluid. And that, of course, is the remarkable technology, right? It's that it's able to impute what the glucose level is in the blood without actually having to sample the blood. That's the magic of these things. Knowing you, I suspect I already know the answer, but I'll ask it anyway. Have you looked at your CGM and compared, say, like your three-month data to an HBA, your HBA, once C? Of course. And see how to, yeah. Yeah, and there's no comparison. So because I actually have something called beta thalassemia minor, or I carry the trait for beta thalassemia, I have tiny little

red blood cells, or as my roommate in med school of matma cormic used to call it, shite for blood. The size of my red blood cells is very small. So my mean corpuscular volume and mean corpuscular hematocrit are very low. I'm not anemic because I make up for it by having a lot of them, so I have a lot of red blood cells, they're just all very small. So I have normal hemoglobin hematocrit oxygen carrying capacity, but my hemoglobin A1C always runs high. I've measured it as high as 5.8. The lowest I've ever had measured is 5.1, but anytime I've measured it, because I've been wearing CGM for almost six years now,

if I go and check my A1C versus my trailing 90-day CGM, it almost always suggests that the hemoglobin A1C is higher by 0.5 to 0.8. If I measure a 5.7 on the hemoglobin A1C, it's overstating my blood glucose, and it should really be about a 5.1 or a 5.2. And we see the opposite in some people. We have some patients where their CGM is actually showing us a much higher level of average blood glucose than what their hemoglobin A1C predicts. So it's important to understand, hemoglobin A1C is a measurement that predicts average blood glucose.

CGM actually gives you average blood glucose and you can reverse engineer an imputed A1C. It's obviously the latter that is much more interesting because you're directly measuring the variable of interest. Yeah, it's amazing. It's amazing technology. It's the difference between like a snapshot and a movie. Yeah, entirely. And from when I started wearing these things nearly six years ago, I thought, I don't

know why everyone in the world isn't wearing it, notwithstanding the cost and the logistics of it. The obvious reason why everyone wasn't wearing it was their cost prohibitive and certainly back then they were quite involved, but they're getting better and better and better. I'd like to believe that there will be a day when you go to your first visit at your doctor or prior to your first visit with your doctor, they mail you a CGM and you wear it for 30 days and that data is looked at by your visit with your doctor, they mail you a CGM and you wear it for 30 days, and that data is looked at by your doctor and your doctor.

By the time you arrive in the office, he or she has that information. And instead of looking at an A1C or a fasting glucose, they can really look at what your glucose excursions have looked like over a period of time. In the real world. They do that with, I guess, the things look fishy, but they'll do it with its fig monometer.

They'll send you home with a blood pressure monitor and you'll take it every so often, maybe three times a day, whatever it is, to get a look at your blood pressure that way. Right. We do that with our patients. Most of our patients, there's a particular blood pressure monitor. We fancy and we have them keep it at home. We have a special log. We have a method that we want them to go about doing it, recording it, and we'll track that as well.

Unfortunately, in the wearable space, blood pressure is still far from primetime. We've tried a bunch of the wearables in that space and have not been impressed yet. I think there's going to be wearables in the blood pressure space soon. Okay, so where do you want to start on this? Because I know that part of the question that was posed

is what are the metrics that we track? I want to go back and state my thesis, right, or call it my hypothesis, I guess. My hypothesis is that outside of the formal diagnosis of type two diabetes, so now I'm referring to what the person asking the question called as, quote, unquote, normal people. It's important that we leave quotes on that because I'm going to argue that that term has no meaning. But in the non-diabetic, which may be a better

way to describe it population, what is my argument? My argument is the following. Lower average blood glucose is better. A hemoglobin A1c of 5.1 is better than a hemoglobin A1C of 5.5, even though neither of those people are anywhere near having type 2 diabetes. 2. A more you can minimize glucose variability, the better. And of course glucose variability is very difficult to measure without a CGM. Using a CGM, the standard deviation is the obvious mathematical tool to do that. And lower is better. I'm stated another way.

If you have two people who both have an average glucose of 100 milligrams per desoleter, which by the way, corresponds to about a hemoglobin A1C of 5 to 5.1, which would be excellent. And one of them has a standard deviation of 10 milligrams per desoleter. And one of them has a standard deviation of 10 milligrams per deciliter, and the other one has a standard deviation of 20. The person with the lower one is better off.

Third, minimizing glucose peaks is important. The respective of the first two things, I said, average glucose and variability. Although obviously the more peaks you have, it's going to all things equal push up glucose and it will certainly increase variability. But I would argue specifically that glucose peaks are problematic and that we want to minimize them. Getting a little bit ahead of myself, what are the three metrics we are constantly tracking in our patients and what am I constantly tracking in myself?

Thank you for listening to today's Sneak Peak AMA episode of the Drive. If you're interested in hearing the complete version of this AMA, you'll wanna become a member. We created a membership program to bring you more in-depth exclusive content without relying on paid ads.

Membership benefits are many and beyond the complete episodes of the AMA each month, they include the following. Redeculously comprehensive podcast show notes that detail every topic, paper, person, and thing we discuss on each episode of the drive. Access to our private podcast feed, the qualities which were a super short podcast typically less than five minutes, released every Tuesday through Friday, which highlight the best questions, topics, and tactics discussed on previous episodes of the drive.

This particularly important for those of you who haven't heard all of the back episodes becomes a great way to go back and filter and decide which ones you want to listen to in detail. Really steep discount codes for products I use and believe in, but for which I don't get paid to endorse, and benefits that we continue to add over time. If you want to learn more and access these member-only benefits, head over to peteratia-md.com-forward-slash-subscribe. Lastly, if you're already a member, but you're hearing this, it means you haven't downloaded our member-only podcast feed, where you can get the full access to the AMA, and you don't

have to listen to this. You can download that at peteratiamd.com forward slash members. You can find me on Twitter, Instagram, Facebook, all with the ID, peteratiamd. You can also leave us a review on Apple Podcasts or whatever podcast player you listen on. This podcast is for general informational purposes only, does not constitute the practice of medicine, nursing, or other professional health care services, including the giving of medical advice. No doctor-patient relationship is formed. The use of this information and the materials linked to this podcast is at the user's own risk. The content on this podcast is not intended to be a substitute for professional medical advice,

diagnosis, or treatment. Users should not disregard or delay an obtaining medical advice from any medical condition they have, and they should seek the assistance of their healthcare professionals for any such conditions. Finally, I take conflicts of interest very seriously. For all of my disclosures in the companies I invest in or advise, please visit peteratiamd.com forward slash about where I keep an up-to-date and active list of such companies. you you