I recently read a study where a group of medical students were given continuous glucose monitors (CGM) to wear for a time to help them understand blood glucose control. ‘Students … shared that the experience enhanced their understanding of nutrition and metabolism, was valuable to their medical education and would influence their future patient care’.
‘Metabolic Health Immersion for Medical Education: A Pilot Program with Continuous Glucose Monitors in Medical and Dental Students’. https://doi.org/10.1177/15598276221119989
I decided to invest in one of these to confirm my understanding of how the body works, experience using a CGM, and then share the experience with readers. I live in New Zealand and chose a Dexcom G7 monitor which I could purchase on-line for NZ$135 plus freight. This would last for 10 days and provide continuous measurement of my glucose levels every 5 minutes. No prescription or prior registration of any kind was required. The data from the sensor links to my smartphone providing a very useful visual picture of what is happening with my glucose all day and night. There is a lower cost, less featured, option for about $100 sold as the Dexcom ONE+.
It arrived ready to go with very clear instructions plus links to video instructions, and I installed it on the back of my upper right arm. The installation is mostly painless and additional tape is provided to ensure it is secure for the full term. I found it easy to wear and could forget about it most of the time, except when trying to avoid getting it too wet in the shower and ensuring that I did not rip it off when changing clothes. I used it at the gym and also while running.
I downloaded the Dexcom app and after a 30 minute warm up and pairing, started to receive glucose information. It was happy so long as my phone was less than 6 meters away so I had to shift my overnight charging station to the bedroom. Now I could see what was happening inside my body from everything I ate, all my exercise and what was going on as I slept overnight.
I could switch the display to the US mg/dl glucose measurement or the mmol/L scale used in NZ.
Here is an example in mmol/L of a portion of the latest 3 hours information presented:
I discovered that I have very steady blood sugar control. In all the 10 days, I only had 2 single instances where the blood sugar went outside the “preselected normal” limits of 3.9 to 10.0 mmol/L. (70 - 180 mg/dL) Although I am over 70, this result is not surprising as I have been eating a low carb (keto) diet for 5 years now with the specific objective of managing insulin. My diet is well described in my book ‘Take Back Your Health’ selling on Amazon or in my blogs at www.takebackyrhealth.com. As you probably know, the body manages glucose to a very tight level and when the level rises, it releases insulin which signals the muscles, liver and mitochondria to pull the excess glucose out of the blood. The picture presented above shows clearly the glucose level rising following a meal and then coming down again quite quickly to lower levels. This lowering is the action of the insulin.
My lowest reading was during the night while sleeping at 3.4 mmol/L (61.2 mg/dL) and my highest was 10.1 mmol/L, (181.8 mg/dL) following a large date scone eaten with lunch. The impact of different foods was very obvious with isolated sugary food such as a sweet biscuit raising the glucose immediately. The whey protein shake I sometimes consume in the morning did not shift the reading.
Bread, even sourdough bread and refined flour products had the biggest impact and raised glucose the highest. The lowest reading during the night followed a unusual late evening ice cream and is likely caused by a high glucose sensitivity I probably have due to the low levels I usually experience. It could be that the insulin spiked a little too high causing an over reaction. However, I did not know any of this and slept peacefully on until morning.
The sequence of eating, and what was already in my stomach when the glucose arrived, also made an obvious difference. I tested a banana and peach pie on two different occasions. The first time it followed a large very low-carb meal with chicken, cauliflower rice, stir fried vegetables and home made satay sauce. The marker hardly shifted. I ate the rest of the pie following a small bacon and eggs meal , also low carb, and the marker danced up rapidly showing a large glucose spike. Clearly having a larger amount of food in the stomach when the glucose (peach pie) arrived made the difference as bacon and eggs on another occasion did not move the needle.
I had expected to see a more obvious indication of when I was burning fat and when I was burning glucose, but it was not clear. I know that I was burning fat predominantly in the mornings as on some days I do not eat until after midday and had no feeling of hunger at all. The morning graph showed a very steady line. The example shown above is a 2:45 pm, (60 gram carb, 48 gram protein) lunch (first meal of the day) showing the transition from a fasted state, metabolizing fat, to a fed state, metabolizing glucose.
A big surprise was the volatility of the readings overnight with what appeared to be cycles of glucose falling gently, followed by a small rise and then resuming falling gently again over about 2 hourly cycles. My explanation: as glucose went low it may have triggered cortisol to raise glucose levels again and repeated. Again this was overnight and I was fast asleep. The monitor line also stayed mostly flat for my gym sessions and 3km runs. I had expected it might rise.
The monitor did make me conscious of what I was eating and apart from occasions when I deliberately chose to see what would happen, I kept to my preferred diet. I used the app ‘Easy Diet Diary’ which is excellent and simple to use, to record an accurate food log. This allowed me to easily see the impact of higher protein or higher carbs on the glucose readings. The food diary reminded me that focusing on low carb has less value if the food is very high calorie. For example, Lindt dark >90% chocolate is very low carb and did not move the monitor, but still punches a high calorie count at 119 calories per 20gram square.
The more I used the monitor the better results I was getting as I learned to manage my eating and diet choices. I found it definitely influenced what I chose to eat. My best day was my final day as I was getting better at managing what and when I ate. Dexcom also provides a free app titled ‘Clarity’ which provides detailed reports and summaries, suitable for sharing with your health professional.
The monitor stayed in place and worked perfectly for the whole 10 days. In fact, it required a strong pull to dislodge when time came to remove it. Perhaps anyone who is concerned about possible pre-diabetes, or just wants to learn how to manage this critical macro at a time we are assaulted with glucose in almost all food, would benefit from a similar 10 day experiment. You get glucose from carbohydrates, so a low-carb diet should keep glucose low. Although I eat a low-carbohydrate diet, I could see that my body ensures an adequate level of glucose at all times. It does this by making glucose from fat and protein if required, by a process called ‘gluconeogenesis’ ensuring I have sufficient for my red blood cells and my brain. My carbohydrate consumption over the test period averaged 99 grams per day which is higher than I would like. A can of Coke delivers 35 grams of carbs and a small bottle of ginger beer delivers 40 grams. Two slices of white toast about 27 grams of carbs.
If you are not doing any glucose management of your diet at present, I would recommend you begin doing so for your health and quality of your future life. Excess glucose and excess insulin are both toxic, damage many elements in the body, accelerate aging, encourage fat accumulation and, long term, will be detrimental to your health.
For me arguably the greatest benefit was that it confirmed, with concrete evidence, all the guidance I have poured into my book, my consulting and my blogs about managing your diet by minimizing carbohydrates, eating medium to high protein and plenty of good quality animal fats. At 73, I am on zero meds, have normal blood pressure, a BMI of 24, sleep soundly and now also know I have good blood sugar control.
For more free reading like this, see my blogs or link to my book at www.takebackyrhealth.com. Seek professional medical advice before making dietary changes, particularly if you are on medication. Contact me if you have questions or for diet consultation.
Good health, George Elder, MBA, Diet Research Reviewer, Dip. Nutrition.
“The greatest thing you can do for your health, is eat better.”
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