Home / Learn / Rethinking blood sugar tracking: is it helpful or harmful?

Rethinking blood sugar tracking: is it helpful or harmful?

3 February 2025

By The Gut Health Doctor Team

Dr Megan Rossi in a lab looking through a microscope

Everyone, from Instagram influencers to new prime-time TV shows, is talking about blood sugar monitoring. For those with diabetes, blood sugar monitoring devices, often worn as patches that transmit real-time data to apps, can be lifesaving. But more recently, they are increasingly being used by those without diabetes, i.e. those with a healthy functioning pancreas, the main organ in charge of your blood sugars. These devices turn people’s attention to the glycaemic index of their meals (a measure of how quickly a food affects your blood sugar; high glycaemic index foods get broken down faster and therefore give more of a spike to blood sugar) and a focus on preventing sugar spikes.

It’s a trend that continues to gain momentum and is often promoted on social feeds by people of influence, claiming that reducing these spikes is the key to overall health. But while tracking your blood sugars may sound like a high-tech and cutting-edge way to “optimise” your health, is it more hype than helpful? Let’s explore the challenges and hidden truths behind this craze.

Blood sugar 101: A quick recap

Before diving into the science, let’s start with some basics:

Blood sugar = glucose, your body’s go-to energy source, created from digested carbs.
Insulin, the “key hormone” produced by your pancreas, helps shuttle glucose from the blood into cells for instant energy or storage when needed later.
Your body dips into these glucose stores when exercising, fasting, or needing an energy boost.
Prolonged high blood sugar in the case of diabetes (when insulin isn’t doing its job effectively) can harm blood vessels, making them less flexible and increasing health risks. It’s linked to complications like heart disease and eye problems.
For people with diabetes, managing blood sugar is vital and often requires lifestyle changes or medication, and this can apply to all types of diabetes: type 1, type 2, and gestational.
For people without diabetes, insulin effectively controls how much glucose is in your blood at any one time, ensuring any sugar spike is short-lived.

Is a spike always a negative?

Firstly, not every blood sugar spike is bad news. Take a banana — sure, it’ll raise your glucose levels temporarily, but it also delivers various types of dietary fibre to nourish those gut microbes, disease-fighting phytochemicals (including catechin, a type of flavonoid), potassium for heart health, and vitamin B6 to support brain function. Now compare that to a piece of fried chicken, which, because it is very low in carbs, won’t cause a glucose spike. Which do you think is better for your health? That’s a pretty easy answer… (but you can check out this reel if you need a little more convincing).

Although there is a clear disconnect between health and blood sugars in the above example, most people will use their common sense and continue to go for the banana over fried chicken. But, for the less apparent comparisons, it can trip people up. This is something we often see in clinic where this fixation on reaching flatlined blood sugar levels steers people away from nutritionally loaded options like porridge oats for breakfast, which are rich in beta-glucan (to lower cholesterol) and instead, they opt for carb-free (and fibre-free) options, like fried eggs. This trend has also demonised fruit such as watermelon, as it’s one of the higher GI foods, yet it’s packed with skin-protecting lycopene and boasts other phytochemicals such as carotenoids and cucurbitacin E, all with antioxidant powers.

But here is the truth: a short spike in nutrient-dense foods is far less concerning than the long-term impact of skipping them altogether. In fact, there is still no convincing evidence that a short spike negatively impacts otherwise healthy people. Most of the claims around the negative impact of blood sugars have been extrapolated from studies in people with diabetes, which differ not only in how their metabolism works but in the duration of the sugar spikes (remember, insulin is very efficient at preventing prolonged spikes in those without diabetes, even if you were to eat a large pack of sweets).

The four challenges of fixating on blood sugar

Here is a recap on why closely monitoring your glucose if you don’t have diabetes (or prediabetes) can come with a few pitfalls:

1. Data drama: Glucose spikes naturally occur after meals and aren’t inherently harmful in those without diabetes. In a healthy person, insulin handles them like a pro, bringing the level down to normal within minutes.

2. Deficiency drivers: Skipping nutrient-rich options like wholegrains and fruits to “keep it steady” can leave you deficient in key nutrients. Take wholegrains: they contain unique types of fibre that help cut cholesterol and the risk of heart disease and feed anti-inflammatory gut bacteria. Are you better off with or without?

3. A question of quality: Excluding certain foods impacts nutrition, but it isn’t the only area of health that is impacted. One study, which included almost 3000 Australians, found that a restrictive eating approach led to an overall lower quality of life.

4. Wallet woes: Those fancy monitors and apps don’t come cheap and have little evidence of long-term benefit for those without diabetes (the science is shaky and has a long way to go).

It’s not just about food

Did you know that blood sugar levels are influenced by much more than just what you eat? Many surprising factors could impact your sugars, which are often mistakenly attributed to what people have eaten, creating more food fears and confusion.

A man in front of his laptop with his head in his hands

Stress

Elevated cortisol levels can raise blood sugar. In one study, scientists asked people to do a maths test and then gave them a meal. They had the same meal on another day without the test. The research, published in the Journal of Diabetic Medicine, revealed that blood sugar rose significantly higher on the maths test day. The theory is that stress hormones can slow insulin release.

Sleep

Poor sleep disrupts glucose metabolism. In a small study published in The Lancet, 11 men were restricted to four hours’ sleep for six nights and then allowed 12 hours for another six. Their blood sugar after eating the same food was higher on the restricted sleep days.

Previous meal

A Toronto University study showed that eating dinner with lentils instead of a protein drink led to lower blood sugar levels after breakfast the next day, despite the exact same breakfast.

There’s also the impact of menstrual cycles (for women), exercise, gut health, medications and more…

A smarter (and cheaper) way to track health

Instead of obsessing over glucose, try focusing on your plant points. How many different plant-based foods can you eat in a week? And how many of the Super Six plant groups a day? Not only is this approach more enjoyable and simple, but research shows that eating more diverse plants is linked with better gut health, heart health, and beyond (this is something that our team at King’s College London is currently investigating in a randomised clinical trial). Plus, it’s a lot more rewarding (and beneficial for your wellbeing) than worrying whether a bowl of fruit will spike your sugar. Check out our free recipe hub for delicious inspiration to boost your plant points.

Takeaway

For people with diabetes, blood sugar monitoring is essential. But for everyone else? It’s not the be-all and end-all of health. In fact, chasing a “perfect” flatline can lead to unnecessary stress and often poor dietary choices. Health isn’t about numbers on an app; it’s about feeling your best.

The real key? Enjoy a balanced diet, focus on plant points and fibre diversity, and let your gut do its thing. So grab that banana, and give your body and gut the nutrients it craves.

If you are in doubt or concerned about your health or blood sugar levels, please consult healthcare professionals to make informed decisions for your wellbeing. Or, if you would like more tailored nutrition support based on your personal health goals, contact our specialist dietitians at The Gut Health Clinic.