29. Continuous Glucose Monitoring | Data, Patterns & Beyond the Hype

In this episode of Mohivate, Dr Mohi Sarawgee explores continuous glucose monitoring through the lens of metabolic health, bringing clarity to one of the most talked about and most misunderstood tools in modern wellness.
The CGM is everywhere. On social media arms, in wellness programmes, in dinner party conversations. But what does it actually measure? What is the science genuinely telling us? And who actually needs one?
This episode covers how CGMs work, what glucose patterns really mean, the science of glycaemic index and glycaemic load, why two people can eat the same meal and have completely different responses, and what advanced glycation end products tell us about long term health.
It explores how to read your own data, what HbA1c misses, and who should and should not consider wearing one, with honest clinical guidance and no agenda.
Grounded in science, personal experience, and a mild voluntary obsession with data, this is a warm, honest and genuinely useful conversation about glucose, metabolic health, and what your body has been trying to show you all along.

References:
1. Glycaemic Index and Glycaemic Load — Food Reference
University of Sydney International GI Database. Search GI and GL values for thousands of foods:
https://glycemicindex.com/gi-search/
2. Individual Variation in Glucose Response — The PREDICT Study
Berry SE et al. Human postprandial responses to food and potential for precision nutrition. Nature Medicine. 2020;26:964–973.
https://www.nature.com/articles/s41591-020-0934-0
PubMed:
https://pubmed.ncbi.nlm.nih.gov/32528151/
3. The 42 Factors — Further Reading
The PREDICT study machine learning model used 42 individual factors to predict glucose response. For a detailed accessible breakdown of factors influencing blood glucose, see also:
https://diatribe.org/diabetes-management/42-factors-affect-blood-glucose-surprising-update
4. Post-Meal Walking — 10 Minutes Immediately After Eating
Hashimoto K et al. Positive impact of a 10-min walk immediately after glucose intake on postprandial glucose levels. Scientific Reports. 2025.
https://www.nature.com/articles/s41598-025-07312-y
Supporting systematic review:
Engeroff T et al. After Dinner Rest a While, After Supper Walk a Mile? Sports Medicine. 2023;53(4):849–869.
https://pubmed.ncbi.nlm.nih.gov/36715875/
5. Soleus Pushup Pilot Study
Elek D et al. The Efficacy of Soleus Push-Up in Individuals with Prediabetes: A Pilot Study. Sports (Basel). 2025;13(3):81.
https://pmc.ncbi.nlm.nih.gov/articles/PMC11946342/

Just a gentle reminder: this episode is for information, education, and inspiration only. It’s not a substitute for your doctor’s advice. For any personal health concerns, always seek guidance from your doctor.

Transcript

SPEAKER_00 0:04

Hi everyone, welcome back to Mohivate. I'm Dr. Mohi Saraugi, a GP by profession, but here I'm swapping prescriptions for perspective. A few weeks ago, we started a series on metabolic health, and if you've been following along, you will know that metabolic health is a large umbrella. Today we are stepping under a very specific and a very tiny part of that umbrella. Because if you spend any time on social media, you will have seen it. Someone holding up their arm, a small white disc tugged just above the elbow, telling you it has completely transformed their relationship with food, or a caption that says simply, I can never eat rice again. And my personal favorite, someone at a dinner party spending the entire evening explaining what they can and cannot eat. We all know that person. That little disc you may already know is a continuous glucose monitor, a CGM, perhaps the most talked-about tool in the metabolic health conversation right now. Today on Mohivate, let's slow down and look at it. What do these devices measure? What is the science genuinely telling us? And who actually needs one? A genuinely useful conversation grounded in science, and I should mention in personal experience too. Because I have now worn one three times in the last three years. Once for my patients, once out of curiosity, and the third time, well, I must confess I'm wearing one right now as I record this, which either makes me very thorough or someone with a mild voluntary obsession with data, devices, and numbers. My pancreas and I are in constant communication. Whether we are on speaking terms is another matter. So let's begin. What is a continuous glucose monitor? For decades, and still the most common method today, checking blood sugar meant a finger prick. One number, one moment in time, like checking the weather once at noon and deciding that represents the entire day. A CGM gives you a film instead of a photograph. A small sensor, roughly the size of a 2 pound coin, sits on the back of your upper arm or abdomen. Inside it, a tiny filament, barely thicker than a hair, sits just beneath the skin, measuring your glucose every few minutes and sending the data wirelessly to an app on your phone. Hundreds of readings a day. Here's what I find genuinely elegant. It does not measure glucose directly from your blood, but from the fluid around your cells called interstitial fluid. That means there's a small lag of around 5 to 15 minutes behind your bloodstream. For most purposes, it doesn't matter, but it's worth knowing. So if you're wearing a CGM and your graph looks alarming immediately after eating, give it 10 minutes before catastrophizing. A CGM measures one thing only glucose, not insulin, not cortisol, just glucose. And glucose, as we will see, tells you something, but not everything. If you heard episode 26 on insulin, this is your quick refresher. Every time you eat, particularly carbohydrates, your body breaks food down into glucose. Glucose enters your bloodstream, blood sugar rises, and your pancreas releases insulin, the hormone that helps glucose move into cells to be used or stored. In a healthy body, the system is elegant. Glucose rises, insulin response, glucose comes back down, order is restored. That is the system a CGM is watching quietly, continuously, day and night. Now, before you put one of these sensors on and panic at your first spike, let's establish what normal looks like. In a healthy person without diabetes, fasting glucose sits between 3.9 and 5.5 millimol per liter or 70 to 99 milligram per deciliter. After eating, it rises. That is expected. Studies show that healthy people spend around 93% of their day between 3.9 and 7.8 millimol per liter or 70 to 140 mg per deciliter. Postmeal glucose peaks around 60 minutes after eating and returns to baseline within 2 to 3 hours. What matters is the pattern, not the single spike. Because the wellness industry has taken thresholds developed to assess risk in diabetic populations and applied them to healthy people without adjustment. A body without diabetes is designed to manage glucose rises. That system exists for a reason. Trust it a little. The app flashing a rise after your meal is not an ambulance, it is lunch. So why does it matter when glucose rises too much too often? It is not about the glucose itself. It is about what happens next. Every time your blood glucose rises, the pancreas releases insulin to bring it back down. In a healthy body, if you are eating three meals a day, that means three rises, three insulin responses. But someone snacking constantly, biscuits, sweets, sugary drinks, processed foods is asking their pancreas to respond not three times, but ten, twelve, fifteen times a day. And over time, the cells begin to ignore the signal. Think of it like knocking on a door. Once or twice, the door opens easily. Knock 10 times a day for years, eventually the person inside stops answering. This is insulin resistance. The cells in your liver, your muscles, your fat tissue become less responsive. The pancreas compensates by producing more insulin and gradually glucose control declines. The glucose is the signal. What you're really watching on a CGM is how hard your pancreas is working and how well your cells are responding. 10 spikes a day versus 3 is a fundamentally different demand on your body. If you wear a CGM, one thing becomes obvious very quickly. The same food does not always produce the same glucose response. And that is where two helpful ideas come in: glycemic index and glycemic load. Glycemic index or GI measures the speed at which a food raises your blood glucose. Different foods have different GI values, but GI tells you only the speed. Glycemic load tells you how much of an impact that food is likely to have in the portion you actually eat. Think of it like a car. GI tells you how fast it can go. Glycemic load tells you how far it travelled. Both matter. Let's take two examples. Watermelon has a high GI, but a normal slice is mostly water and very little carbohydrate. So the glycemic load is low. Your CGM will barely move. White rice has a more moderate GI, but one cup contains a significant amount of carbohydrate. The glycemic load is high. Your CGM will tell a very different story, despite white rice having the lower GI number. This is why GI alone can mislead you. What matters is speed, quantity, and context, and they all show up on your CGM. The GI of a food also changes depending on how you prepare it, how long you cook it, and what you eat alongside it. I know, as if life needed another variable. Pasta cooked al dente has a lower GI than the same pasta cooked soft because the more you break down the structure of a starchy food through heat and time, the faster your body digests it and the quicker glucose enters your bloodstream. Your pasta has feelings about how long you cook it. Apparently, so does your pancreas. And it is not just what you eat, it is what you eat it with. Protein, fat, and fibre slow digestion, so glucose enters the bloodstream more gradually and the spike is smaller. Don't make white rice your enemy. Eat it alongside plenty of vegetables, adequate protein, and a drizzle of fat. The curve changes completely. Context is everything. And finally, the fridge moment. Cook your potato, rice, or pasta, cool it in the fridge, then reheat it. In some studies, cooling and reheating has reduced the glucose impact noticeably. Cooling converts some starch into resistant starch. Your body digests it much more slowly, almost like fiber itself. Same food, prepared differently, metabolically, a completely different story. And you can see that in real time on your CGM. And once you see it, you cannot unsee it. Now here is something the research has confirmed and something I experienced firsthand. Two people can eat exactly the same meal and have completely different glucose responses. I ate a banana, my glucose spiked. A colleague ate a similar banana, nothing. Banana next time blended with a protein, fibre, and fat, my spike was noticeably smaller. This is not just anecdotal. The research confirms it. In the PRIDICT studies involving a thousand people in collaboration with King's College London, Harvard, and Stanford, researchers found that even identical twins had very different glucose responses to the same meals. Genes account for only around 30% of the variation in your glucose response. The rest comes from everything else: your gut microbiome, sleep, stress, exercise, meal timing, time of day. 42 factors have been identified that influence your individual glucose response. 42. Let that sit for a moment. Don't worry, I'm not going to list all of them here. I've linked the original research in the show notes for anyone curious enough to go down that rabbit hole. And it is a fascinating one. One diet does not fit all. We all respond differently. And understanding how to eat is one of the most valuable things we can do for our metabolic health. And it does not need an expensive subscription to start eating better for your own body. That knowledge is free and it belongs to everyone. One more concept worth understanding advanced glycation end products or AGEs. When glucose stays elevated persistently over time, it begins to attach itself to proteins and fats in your body in a process called glycation. The same chemical reaction that browns food when bread toasts, when onions turn golden, the mayard reaction. That beautiful browning caramelization you see in cooking. The same chemistry happening quietly inside your tissues over time. Because some proteins, collagen in your skin, your blood vessels, nerves, your eyes have very long lifespans, so the effects accumulate over years. AGs are associated with accelerated skin aging, vascular stiffness, cardiovascular disease, kidney and nerve damage, joint stiffness, and the long-term complications of poorly controlled diabetes. But this is the important distinction. This is about sustained elevated glucose over time, not a single postmeme spike. One spike is not browning your proteins. Persistent exposure is what shapes long-term health, and that is exactly where a CGM can be useful. Not as a tool for panic, but as a way of noticing patterns early enough to do something about them. So how do you actually read a CGM? First, your fasting glucose. When you wake up before eating anything, your glucose should sit between 3.9 and 5.5 millimol per liter or 70 to 99 milligram per deciliter. This is your baseline. If it is consistently above 5.6 millimol per liter or 100 milligram per deciliter, that is worth a conversation with your doctor. After eating, glucose rises. In a healthy person, it will usually return to below 7.8 millimol per liter or 140 mg per deciliter within 2 to 3 hours. What matters is the pattern. Is it repeatedly going above 10 mm per liter or 180 mg per deciliter after means? Does it stay elevated beyond 3 hours? Is your fasting glucose trending upward over time? Then look at the shape of the spike. A spike that rises up, peaks, and comes back down cleanly to the baseline. A mountain shape is what you're looking for. A plateau shape suggests your body is taking longer to bring glucose back down. And then there is a crash where glucose drops sharply, sometimes below baseline. That crash is reactive hypoglycemia. It explains the afternoon energy dip, the brain fog, the sleepiness, and the sudden hunger even after a full meal. Your 3 pm slump finally explained on a graph. Now zoom out. Glycemic variability is how much your glucose swings across the day. A stable profile, gentle rises and falls, is healthier than sharp peaks and crashes, even if the average looks fine. Look at your graph. You're aiming for a smooth curve, not a theme park ride. Then look at time and range. It will be on the app's summary screen. Time and range is the percentage of the day your glucose spends between 3.9 and 7.8 millimol per liter or 70 to 140 milligram per deciliter. In healthy people without diabetes, that is often very high, usually above 90%. If it is consistently below that, it is worth a conversation with your GP. For people with type 1 or type 2 diabetes, the target is above 70%. Mine, after 3 attempts in 3 years, is currently 100%. Third time lucky. As it turns out, my pancreas and I are on speaking terms after all. Then the overnight picture, one of the most underrated parts of a CGM. Overnight glucose should sit between 3.9 and 5.5 millimol per liter or 70 to 99 mg per deciliter. Spikes overnight? Ask what you ate in the 2 to 3 hours before bed. You would never know otherwise because you were asleep. And HBA1C alongside your CGM. HBA1C, glycosylated hemoglobin, is your 3-month average glucose. It remains the cornerstone of diabetes monitoring, but it is an average, and an average hides the story. Two people can have identical HBA1C results and completely different glucose patterns. The CGM shows what the average was always concealing. They are not competing, they are complementary. Your HBA1C may look perfectly normal, and yet your CGM may be telling a more nuanced story. The early whispers of insulin resistance long before any diagnosis. That story is worth understanding. So who should actually consider using a CGM? People with type 1 diabetes, non-negotiable. It is life-saving, real-time glucose, alerts, prevention of dangerous lows. It has transformed care. In the UK, the NHS provides CGMs for most people with type 1 diabetes. Then, in type 2 diabetes, pre-diabetes or insulin resistance, including PCOS, fatty liver disease, or metabolic syndrome, a CGM can offer useful insight beyond HBA1C. Then high-risk individuals, strong family history or previous gestational diabetes. Seeing the effect of simple changes like a short walk after means can sometimes be more persuasive than doctor's advice alone. If you're simply curious, one sensor, 14 days, approached with curiosity rather than anxiety can be informative. Now the reasons to think twice. If you have a history of disordered eating, food anxiety, or an obsessive relationship with data, please be cautious. Constant visibility can amplify those patterns. And if you're completely healthy with no metabolic risk factors, your body is likely managing glucose well already. You don't need a sensor to confirm that. If you do choose to use one, keep the intention clear. Do not let the app become the point. The insight is the point. So why did I try a CGM? Partly because my patients kept asking. I knew how to guide someone with diabetes, but for a non-diabetic person, the conversation was different and I wanted to understand it properly. And partly because I have PCOS, which comes with insulin resistance, something I have navigated, reversed, and been humbled by more than once. The universe has a way of reminding you to practice what you preach. So I wore a sensor, and what I saw surprised me even as a doctor who already knew the science. Seeing your own glucose patterns in real time makes it personal in a way that knowledge alone never quite does. Before I close, let me leave you with five things I genuinely learned. Not from research, from my own graph, my own body. Number one, plan your meals. Meal planning was the biggest shift for me. Nothing obsessive, simply knowing what is on your plate before you sit down, starting with protein and fiber. You find your rhythm. If you genuinely want to support your metabolic health, this is where it begins. Number two, move after eating immediately. Not a workout, 10 minutes of walking right after your meal, not 30 minutes later. Moving while glucose is entering your bloodstream helps your muscles absorb it directly and flattens the spike. Once you see it on your graph, you will never sit straight back down after a meal again. Encourage your children as well, maybe just to take 200 steps after their meals. And please don't walk and eat. Sit down and have your meals. Number three, sleep is metabolic medicine. One bad night showed up the next morning. Higher baseline, bigger spikes, slower recovery before I had eaten a single thing. Number four, stress has a glucose signature. A difficult day, a hard conversation, the reach for that piece of chocolate between patients. It all showed up in black and white. Not because of what I ate, but because of what I was carrying. And number five, discernment. Not every glucose hack works for everyone. Social media moves fast, science moves slower. What works on someone else's graph may do nothing on yours. Your biology is not a trend, and your CGM will tell you what actually works for you. After 14 days of data, graphs, spikes, patterns, reflections, I sat with everything I had seen. The message at the bottom of all of it did not require a glucose monitor. They are things we have known for decades. What the CGM did was make them visceral. It put my name on them. It showed me my own data, reacting to my own choices in my own body. And that I felt was genuinely powerful. But the power is in the insight, not in the ongoing surveillance. The goal was never the number on the graph. The goal was always what you do with it. So here we are a tiny sensor, a real time window into something your body has been doing every Single day since you were born, managing glucose, releasing insulin, storing energy, protecting you. The technology is remarkable, the science is fascinating, and the insight, when used well, with curiosity and without obsession can be genuinely useful. But beneath the graphs and the spikes and the 42 factors, the message is still the same: a nutritionally balanced plate, movement, sleep, managing your stress, sunlight, kindness to yourself and to those around you. That was never in the device. It was always in you. Your glucose monitor did not invent that wisdom. It just made it yours. I hope something today stirred a thought, gave you a smile or simply made you pause. Thank you for listening. I am Dr. Mohi. Until next time, may you keep returning to the conversation your body has been trying to have with you. And may that steadily lead you closer to coming home to yourself.