Insights Into Continuous Glucose Monitoring

Much is made of the latest piece of ‘wearable’ health tech - continuous glucose monitors, made popular by Zoe in 2023.

Continuous glucose monitors (CGM) was first created to advance the standard technology for type 1 diabetics to (as the name suggests) provide real time live feedback on glucose levels.

A hugely convenient upgrade from the previous method of finger prick testing and over the course of the last couple of years, the use of CGM’s has expanded into a market vastly larger than the one that it was first intended for.

Firstly, type 2 diabetics also found them useful to track blood glucose levels and more recently, non-diabetics.

Blood glucose levels are unbelievably tightly controlled by the human body. It is thought that there is only 1 teaspoon of glucose floating around within the blood of your whole body at any single moment in time and if this goes to 2 teaspoons, you are on your way to dying.

The primary hormone that controls blood glucose levels is called insulin which is produced by the pancreas. In type 1 diabetes, patients do not produce insulin and therefore have to self-administer.

This is why understanding what glucose levels are doing for these people is of utmost importance as both hypoglycemia (low blood glucose) as well as hyperglycemia (high blood glucose) can be dangerous and even fatal.

But what about for non-diabetics?

The argument coming out of the nutrition community, especially amplified by Zoe is that understanding what causes your glucose levels to spike will be of benefit, as this will prevent any harsh subsequent drops. Ultimately, fine-tuning what you eat by using your CGM data will be healthier for you.

Well, I just finished wearing one for 2 weeks. Here are a few take-aways.

1) Your sleep quality/quantity impacts your glucose levels more than you think.

How well you slept the night before can impact the way that you respond to glucose, even after eating the same meal. The more underslept you are, the poorer your glucose response, leading to higher glucose levels.

This is not news to most people who were previously into the physiology of blood glucose and insulin resistance, but still profound.

The reason why we want to avoid constantly spiking our blood glucose levels is partly due to the inevitable ‘crash’ that ensues which only sharpens a craving for the next ‘pick me up’ whether that is a coffee, sugary snack or perhaps both.

But the real problem with chronically spiking blood glucose levels is that in type 2 diabetes, microvascular (small blood vessels) damage is seen which can lead to complications such as retinopathy, neuropathy and nephropathy. And type 2 diabetes is the hallmark disease of high blood glucose levels.

If long-term health is important to you, managing glucose levels is important. One of the key ways in doing so is by prioritising sleep.

2) Feelings of hunger does NOT always mean your glucose levels are low.

The term ‘hangry’ has become somewhat colloquial in the way that we express our emotions when we’re hungry and even to most people of the general population, ‘low blood sugar’ is often used as a synonym.

Over the course of the last 2 weeks, I’ve found zero correlations between the two. I’ve felt hungry at times where my glucose levels have been within optimal ranges. I’ve been bordering low with my glucose levels but haven’t felt the urge to eat.

One possible explanation for this is the way that our digestive system is intrinsically connected to our circadian rhythm, our internal clock.

Notice how you start feeling hungry at around your typical meal times. For me, this is around 8am, 12-1pm, 3-4pm and 7pm. I believe this is just our circadian rhythm cueing us to eat by raising our hunger hormone ghrelin.

Now, provided that your main meals have met your nutritional and caloric demands, urges to eat outside of your main meals typically stem from a place outside of true physiological hunger and should be explored if posing issues (weight gain/digestive issues etc).

3) Alcohol is bad news for glucose levels

*Disclaimer* I’m a relatively light drinker with pronounced asian flush (not sure what asian flush is? Google it, it’s interesting and hilarious at the same time).

I denote the above because I realise that there must be an individual uniqueness to everything I’m talking about here. Now, don’t get me wrong, I’m not in the slightest suggesting that alcohol intake could be a net positive for somebody with blessed favourable genes towards alcohol, it almost always does the same thing if consumed in excess which is - leads to unnecessary eating afterward.

But the variation in response is probably going to be dissimilar from person to person.

Although alcohol often contains sugar, I actually saw my glucose levels drop. Which may explain the subsequent reaching of high fat, high sugary pick me up snack.

From the way that the alcohol itself can de-stabilise blood glucose levels, to the potential snacking afterward, to the potential harm it could be causing to your liver (one of the key organs in managing your glucose levels), alcohol consumption in excess is definitely something to re-evaluate.

4) A balanced diet is where the gold is.

Again, nothing new or revolutionary about this, but more of a consolidator.

Everything good that we want from our nutrition intake happens when we enjoy a balanced diet that is inclusive, not exclusive.

When I observed my glucose levels following Christmas dinner (turkey with gravy, roasted vegetables and potatoes, Yorkshire pudding, pigs in blanket, cranberry sauce, Brussels sprouts) it rose to about 8.0 mmol/L which is more than an acceptable peak.

I’ll admit, my portion was probably big enough to feed 2, but the high protein, high veg content really does support a slower elevation in glucose.

It’s also well-documented how fats in the diet can support a slower glucose response and I’ve observed this in the last two weeks too.

Isn’t it convenient how protein and fats do an amazing job at slowing down glucose response? It’s as if the 3 macronutrients were made for each other!

Reinventing the wheel just simply does not make sense :)

References

Briançon-Marjollet A, Weiszenstein M, Henri M, Thomas A, Godin-Ribuot D, Polak J. The impact of sleep disorders on glucose metabolism: endocrine and molecular mechanisms. Diabetol Metab Syndr. 2015 Mar 24;7:25. doi: 10.1186/s13098-015-0018-3. PMID: 25834642; PMCID: PMC4381534.

Hanssen NMJ, Kraakman MJ, Flynn MC, Nagareddy PR, Schalkwijk CG, Murphy AJ. Postprandial Glucose Spikes, an Important Contributor to Cardiovascular Disease in Diabetes? Front Cardiovasc Med. 2020 Sep 18;7:570553. doi: 10.3389/fcvm.2020.570553. PMID: 33195459; PMCID: PMC7530333.