What I learnt from wearing a continous glucose monitor

Marcus and I wore a continous glucose monitor for 2 weeks…

A few people I have spoken to were curious as to why we did this and were interested in the results, so I decided to post my findings on my blog.

This was just an experiment for interests sake. I was curious as to how continous glucose monitors work and I thought it would be interesting to see our own different glycemic responses to various foods…

A continous glucose monitor is a device which constantly measures glucose levels. It’s round and flat and has a small, soft needle which goes into and just underneath your skin and sticks to your skin. Then you scan the device with your smartphone for glucose readings. You can sleep with it, shower with it and exercise with it.

Glucose is the sugar content in your blood. Glucose is what is raised in people who have diabetes. Neither me or Marcus have diabetes but we (initially mostly me) were curious about our individual glucose responses to different foods. This was triggered a few years ago when I heard about a study that was done in Isreal. It concluded that we all have a different gut microbiome and different genetics which caused individual glucose responses to different foods. When people know which foods cause glucose spikes they can better choose appropriate food options for themselves.

So, if you constantly have glucose spikes, your body produces insulin in response to these spikes, but eventually, if you are predisposed, and these sugar spikes keep occurring, your cells become resistant to the insulin resulting in pre-diabetes or diabetes (Type 2 or non-insulin dependant diabetes) and is generally treated with oral medication. If your pancreas is unable to produce enough insulin, you could even get insulin dependant diabetes. (insulin dependant diabetes, or type 1 diabetes as some call it, is a whole different topic because this is the type that mostly occurs due to an unfortunate pathology and not necessarily because of a poor diet.) Marcus and I both have family members with diabetes so we will need to watch our weight and what we eat to help prevent us getting diabetes.

Being a primary care doctor, I like to focus on prevention. I also have many diabetic patients and this experiment helped me to understand glucose levels better so I am better able to talk to my patients about glucose control. It makes a big difference when you test something practically on yourself as opposed to what you read in a book.

Marcus and I didn’t restrict ourselves to certain foods and generally didn’t overdo it either. We ate what we would have eaten if we weren’t wearing the monitors. We exercised like we usually do. One small glitch, we got sick during the second week. Flu-like symptoms that I think was Covid because so many people in town had Covid at the same time. That’s when my glucose especially spiked and it showed me that sometimes it’s not the food you eat but how you are and what you do when you eat the food you eat. The same exact meal eaten when I wasn’t sick caused my glucose to spike more when I was sick. My fasting glucose also seemed higher when I was sick. (It could also be because I was as active as what I usually am?)

I realized that there are so many variables to glucose control. The food you eat, when you eat, in what order you eat your food, what you eat with the same food, cooling and heating the food, quality and duration of sleep, exercising, sickness, stress levels, apple cider vinegar, hydration… It almost feels overwhelming! These are things we hear and read about, but with the continous glucose monitor, it made all these things much more real than what they were before.

Glucose levels are important not only to prevent diabetes. If your glucose levels are constantly elevated, your insulin will be elevated which makes it very, very difficult to burn fat and lose weight. Also, erratic glucose levels (which go up and down a lot) will make you feel consistently tired. Your doctor may do your bloods and say your HbA1c (measures glucose control over 2 month period) is normal, but you won’t be able to see exactly what your glucose is doing with HbA1C.

Yes, some foods are obvious culprits to cause raised glucose… Like cupcakes and bread. I thought rice would be a bit better. But no! Not for me, my response to any rice, white rice, brown rice, parboiled rice was hectic. Rice spiked my glucose even when eaten with protein/fat! Rice really spikes my glucose. More than chocolates! (and I’m not saying I should eat more chocolates.. But can I?) I need to really limit my rice portions or try to avoid rice. And this is good to know. Marcus’s glucose also spiked with rice but not as much as mine. Marcus’s glucose spiked similarly to all carbohydrates including Oats. But my glucose spiked dramatically more with rice than other carbohydrates. Regardless of sickness or exercise. My glucose doesn’t seem to spike a lot with oats.

Now remember, we weren’t very scientific about this. We didn’t measure food or anything. We ate what we would eat. I never realized my average portion of rice spikes my glucose like it does. I also didn’t know that while oats is okay for me to eat for consistency in glucose levels, Marcus’s glucose spiked with Oats. So don’t avoid rice just because I should avoid rice. (Except my siblings should maybe look into this… Perhaps it’s genetic? )

You have probably heard about letting starch (like rice or pap) cool down and reheating it again? It apparently lowers the Glycemic Index in the starch. Well, it really works, few times that I tried it it consistently makes that my glucose raised 1-3mmols less when I tried this trick. That’s quite significant! I wonder what difference it would make for someone with diabetes?

My glucose didn’t spike significantly with any fruits I ate, it spiked with sweet potato (but that could have been due to sickness). Coffee with a little milk, did cause a slight rise in glucose, but it looks like coffee without milk also caused a slight spike…? So I suppose that even black coffee breaks my fast? This helps to know if I would want to attempt a fast. I wonder effect adding MCT oil to coffee would have?

I noticed the significant effect exercise has on blood glucose. Walking after a meal drops glucose quite quickly and stops a spike from going higher.

The amount of water I drank had an effect on my glucose. When I ate when I was thirsty my glucose peaked higher than if I drank more water throughout the day. I must remember to drink water when I’m thirsty. 🤣Seems so obvious! But sometimes one needs to be reminded of the basics!

Apparently blood glucose is more likely to spike if you eat carbohydrates first… I still need to try this, I feel I hardly ever eat anything first. I eat everything at the same time. I probably eat too fast! I need to slow down and experience my food and be more mindful of what I eat.

Alcohol was an interesting one! Alcohol decreased my and Marcus’s glucose levels. We only drank what we usually drink but our glucose didn’t rise with red wine, Savanah or beer! It actually seemed to lower our glucose! And if I had a drink close to bedtime my glucose dropped very low… But then, it seems it gives me a higher fasting glucose in the morning. I also wear a smartwatch which measures my body battery… Alcohol has a negative effect on my body battery if I drink anything more than 1 glass of red wine or 1 small beer. But it does drop my glucose… So, one also needs to take the nutrient value of food into account, not merely its glycemic effect.

We didn’t test what juices or cooldrinks did because we hardly ever drink these anyway… But it would be interesting to still test… Because it should theoretical cause a sharp, high spike in glucose levels. But I am curious to see how high compared to starchy carbs. (I’ll try it sometime and let you know. )

So, to summarize what I learnt from our 2 week CGM experiment : I realized how our food affects us! What we put into our mouths has such a big effect on us. One knows these things but seeing the effects on yourself does make a difference. LlIndividualizing a diet is important. What works for me, won’t necessarily work for you. Exercise (or moving) is beneficial. Sleep is important. Sickness (like flu or Covid) raises glucose levels… (Perhaps eating less when one is sick or avoiding certain foods during an illness is a good idea.) I should avoid eating rice. I can eat oats or fruit without spiking my glucose. Alcohol causes a drop in glucose… But is not necessarily healthy. (But one small glass of something alcoholic is maybe not too bad? But can you limit it to one small glass?) There’s a lot of factors that affect blood glucose and it may feel overwhelming but the basics still remain : Eat real foods, Avoid refined carbs, move more, it’s important to sleep well and no rice for me. 🤣

2 Weeks is too short for this experiment and that’s why I’m starting another 2 week cycle to investigate a bit more…

Have you tried continous glucose monitoring? Any strange or interesting findings?