How blood sugar tracking is changing the way we eat

Blood sugar monitoring is having a moment. With the release of the Glucose Goddess Jessie Inchauspé’s number 1 best-selling book The Glucose Revolution last year, and the development of new blood sugar detection digital health technologies, such as Libre glucose monitoring system, public awareness of the effect of blood sugar on health is growing fast. 

New devices for healthy individuals (as well as diabetics) that monitor blood sugar in real-time, continuous glucose monitors (CGMs) linked to apps to monitor results, from companies such as Zoe, Limbo, Levels and Veri, are hitting the market all the time. And now tech big-hitters Apple and Samsung are developing new non-invasive glucose monitoring programmes for future mainstream use. 

These CGMs are designed to track blood sugar levels after we eat, exercise, have sex, work, stress, or sleep and the idea is that monitoring our responses can help us keep our levels within healthy ranges.

Meanwhile, the evidence around the importance of blood sugar is stacking up: new research by Professors Wyatt, Tim Spector, Sarah Berry and the teams at King’s College London, and the Appetite and Energy Balance Research Group at the University of Leeds shows that dips in blood sugar impact vitality, appetite, sleep and even the gut microbiome.

What is blood sugar monitoring?  

Our food is made of the nutrients carbohydrates, fats, proteins, vitamins and minerals and water which all have roles in the body. We digest our food into glucose and combine it with oxygen we breathe to make energy which is used by every cell in our body. Our brains use 20 percent of this glucose at any given time. Some nutrients release glucose more rapidly than others causing spikes in our blood sugar. Simple carbohydrates, like sugars, and saturated fats, can cause very rapid and high spikes as they produce quick-acting, short-lasting energy.  

Complex carbohydrates (unprocessed, high protein and high-fibre carbohydrates, such as whole grains, vegetables and beans) and monounsaturated and polyunsaturated fats (in nuts, fish, seeds, and dairy), cause smaller spikes providing slow-acting, long-lasting energy. The brain’s hypothalamus detects high blood glucose and releases insulin which decreases our blood sugar levels. 

Low blood sugar levels increase our appetite, making us eat (which is why blood glucose is so linked to appetite and weight). It also triggers the release of cortisol, the stress hormone, and adrenaline, which can make us angry, anxious, less resilient to stress and less able to sleep (think “hangry”). Keeping our blood sugar within healthy ranges can hugely affect appetite for food – and life.  

Low blood sugar levels have also been shown in research to contribute to the release of advanced glycation end-products (AGEs) which are said to damage DNA (increasing the risk of conditions such as cancers) and collagen in our skin (aging our muscles, blood vessels, heart, and skin- wrinkles) enhancing cortisol release. In effect, AGES age you. Blood sugar spikes and ultraprocessed foods also directly affect gut microbiota, impacting the gut-brain axis and immune system (a disrupted gut microbiota is linked to inflammation).

What is a continuous glucose monitor? 

A CGM involves a small wearable blood biomarker sensor in your arm that is linked to an application on your phone. It provides personal continuous analysis of your blood sugar levels throughout the day. It sits in the skin so uses interstitial fluid and not actual blood glucose. 

A healthy fasting blood glucose level is between 3.9 and 5.6 mmol/L and around 7.8mmol/L after a meal. This will be different for those with diabetes (a condition where you either don’t produce insulin (type 1) or are resistant to it (type 2)). 

In healthy people, the body regulates blood sugar the way it does temperature, and everyone has a personalised response, dependent on their own biochemistry. Blood glucose is as affected by what you ate yesterday as today, where you are in your monthly cycle, stress, hydration, exercise, stress, sleep and so many other factors can affect it. Spikes and crashes are normal but the ultraprocessed, high-sugar modern diet is sending our Stone Age hardware haywire.  

Is it just for diabetics? 

Although previously designed for diabetics, more non-diabetics are becoming aware of the benefits of CGM on their stress levels, sleep, memory, and emotions. Celebrities such as Shaquille O’Neal and Davina McCall have been seen wearing CGMs. 

Tom Kavanagh, 76, is a non-diabetic from London who tried CGM technology, in conjunction with a programme called Limbo. He says: “Using a continuous glucose monitor as a non-diabetic seemed like a strange idea at first, but I learned so much about my body so quickly, I realised I was often eating foods that were supplying me with more energy than I needed, faster than my body wanted it.”

Kavanagh says that once he understood that the excess was being stored as fat, he was able to change his habits and lose 10kg, and also feels much fitter than a year ago.

What makes blood sugar spike?

There are lots of factors that affect your blood sugar. High-sugar foods and drinks, such as cakes, sweets and biscuits, honey, fructose in fruit, high-fructose-corn-syrup (HFCS) ultra-processed sweetened beverages, condiments and alcoholic liquors, all cause rapid spikes in blood sugar. 

A sugary dessert or breakfast (an oat milk latte, a Danish pastry, cake), fruit smoothie (where all the fibre has been removed leaving just the sugar) or snack or desert, can cause massive spikes and troughs in blood glucose and insulin response.

By contrast, high-fibre and high protein foods like nuts, fish, meat, vegetables, cheese, tofu, or wholegrains, keep you feeling full of energy for longer.

Low-sugar diets and those containing less processed foods, such as the Mediterranean diet and Nordic diet, which are high in protein, healthy fats such as monounsaturated fats and omega3 polyunsaturated fats and low in simple carbohydrates, are becoming ever more popular as they help keep blood sugar within healthy ranges. 

Muscle building exercise can also help regulate blood sugar, improving our blood glucose response (called our insulin sensitivity). Muscle takes up glucose from the blood, reducing blood sugar levels, and so a high protein diet and exercise can also help improve insulin sensitivity and blood sugar regulation. 

Evidence also shows that adding cinnamon or having fibre and acid with your food (lemons, vinegars, limes, fruit, and vegetables like tomatoes) may help to improve blood sugar responses to meals.   

If you’re thinking of buying one, what should you look for in a CGM? 

You can currently buy CGM devices on the internet for just under £50, however using one without expert guidance can be confusing. They are usually used in conjunction with programmes such as Limbo, Levels, Helloinside, Nutrisense or Zoe.

These translate your blood sugar responses, along with a host of other data on your microbiome and tailor a bespoke diet based on your blood sugar response. However, these programmes are not cheap; prices range for membership plans from £24.99 per month plus £299.99 for the test kit for Zoe, £299 per month for Nutrisense and £160 per month for Limbo, restricting CGM use for many.

Yet as the technology improves, and more tech companies like Apple get in on the action, prices are falling, and the technology is improving.

Are there any drawbacks?

Aside from the cost at present which makes them inaccessible to most people, some worry that CGM use will encourage restrictive diets. Professor Sarah Berry at King’s College London says, “many who follow the Glucose Goddess diet based on blood sugars, now see carbohydrates and sugars as being somehow bad, however all foods can be incorporated into a balanced diet, if consumed as occasional treats.”

What is clear is that what we eat impacts how we feel, look, move, sleep, behave, our children and our future health. Food is medicine and the way it affects you is unique to each individual. There is no good or bad food or right or wrong way of eating as we all have different biochemistry, and thus all have our own version of healthy eating.

CGMs are another key biomarker tool which will help us use biological evidence to tailor our diets, our nutritional medicine, to our own biology. A massive tidal shift in the way we see food, exercise, nutrition, and medicine is coming. The future of health looks personalised.