Postprandial glucose responses in people without diabetes

ZOE’s personalised nutrition programme uses a multipronged approach to create personalised food scores.

We conduct a gut microbiome test, analyse members’ lipemic responses to a standardised test cookie, and assess their postprandial blood glucose responses to the cookie and to their normal diet over a 2-week period. 

We also provide in-app lessons, recipes and food recommendations, personalised food scores and one-on-one support from nutritionists with Association for Nutrition accredited degrees.

We’ll also explain how understanding postprandial metabolic responses can help people make healthier food and lifestyle choices.

CGMs in healthy populations

CGMs are an increasingly important part of diabetes care. Their use in people without diabetes, however, has been more controversial.

It’s well established that elevated blood glucose levels increase the risk of cardiovascular and other diseases over the long term. However, most research in this vein has been carried out in people with type 2 diabetes. 

That said, a body of evidence demonstrates that pronounced glucose excursions in otherwise healthy individuals can increase disease risk. Although there are certainly fewer studies, scientists have been pursuing this line of investigation for some time. 

A meta-analysis of 38 studies involving people without diabetes, published in 2004, concluded that individuals with the most pronounced blood sugar responses had a 27% greater risk of cardiovascular disease compared with individuals who had the smallest responses.

Similarly, a 2013 study involved people without diabetes or heart disease. They found that individuals with larger glucose response after eating had stiffer carotid arteries – the arteries that take blood to the brain. Carotid artery stiffness is a risk factor for stroke. 

ZOE’s initial PREDICT study showed that metabolic responses to the same meal vary significantly between individuals. However, broadly speaking, there’s less intraindividual variation — each person has a similar response to identical meals. 

So, understanding how to minimise postprandial glucose excursions in people with poor blood sugar control could make a significant difference to disease risk.

Time in range

In people with diabetes, time in range (TIR) – the amount of time blood glucose levels are in the recommended target range – helps predict the risk of complications.

In June 2022, ZOE’s scientists published a paper in Current Developments in Nutrition investigating TIR’s links to diet and health in people without diabetes.

The American Diabetes Association’s recommended target range is 70–140 mg/dL, but we used an optimised 70–100 mg/dL range. 

We found that, despite a healthy fasting HbA1c value, individuals who spent less time in the optimised range had higher atherosclerotic cardiovascular disease risk.

Blood sugar dips

While blood sugar ‘spikes’ have received the most attention in the media, ZOE’s research shows that blood glucose dips may also influence long-term health outcomes.

We found that 2–3 hours after a meal, some individuals’ blood glucose levels dip below baseline. 

Learning how to control or counteract these types of glucose excursion could be a powerful tool in regulating appetite and maintaining a healthy weight.

Examining dips

In a follow-up to the ‘big dipper’ paper, we identified how macronutrients influenced the likelihood of blood sugar dips. The research was presented at the American Society for Nutrition conference in 2023.

Of the 654 participants we enrolled, 23% dipped at least 10% below baseline after a glucose excursion. These we classed as big dippers. 

We showed that meals with a higher percentage of energy from sugar and a lower percentage from protein and fibre were associated with larger dips.

In this way, insights into postprandial responses can spur members to naturally modulate their appetite with food choices. 

By focusing on meals with personalised advice involving more plant protein and fibre, they can reduce the risk of glucose dips, which may help them better control their appetite without relying on willpower.

The testing phase

As part of the ZOE programme, members wear a CGM for 2 weeks. As they watch their blood sugar rise and dip in real time, it brings to life the physiological changes that food produces. 

Members also take in-app lessons, in which we explain why blood sugar rises and why it’s normal and healthy. We aim to help people appreciate the wonder of their own biology.

During the 2-week CGM phase, members are encouraged to carry out ‘experiments’.

For one of these experiments, we ask them to eat a slice of white bread. This produces a distinct rise in blood sugar levels. The next day, at the same time, they eat another slice of white bread, this time with peanut butter. 

On another day, we ask them to eat white toast and then go on a brisk, 10-minute walk. Again, this physical activity mutes their blood glucose response.

Seeing the changes in real-time on a smartphone is a powerful way to learn about personal metabolic responses. We believe, and our members tell us, that combined with the lessons and in-app nutrition support, it helps drive better-informed dietary and lifestyle choices.

While the CGM is only one part of the holistic ZOE package, members find it incredibly insightful and surprising. It helps translate theory into concrete steps they can take.