The link between glucose (blood sugar) responses and the foods you eat

We’ve all heard the standard nutrition advice: eat plenty of fruits and vegetables, lean protein, healthy fats, and minimise added sugar. 

While this may be helpful guidance, the reality is that we’re all different and respond uniquely to the same foods based on our physiology. Specifically, glucose responses after eating foods containing carbs can vary quite a bit from person to person.^1,2 

Why foods can raise your glucose levels 

When you eat carbs, your body breaks them down and converts them into glucose, one of your body’s main sources of energy. The glucose then circulates in your bloodstream so that it can get into your cells and be used for energy. 

Your glucose levels naturally rise and fall over the course of the day, but sometimes the amount circulating in your body surpasses what is needed for energy. When glucose becomes too concentrated in the blood, we refer to it as a glucose spike or blood sugar spike. 

It’s natural for your glucose to spike now and then, but research indicates that regular and prolonged sharp rises in your glucose could have a negative impact on your health.³ 

Glucose spikes can occur due to things like stress or a poor night’s sleep, but a common cause is the food you eat. Eating foods that are high in carbs (especially simple carbs like white bread or pasta) results in a greater amount of glucose in your bloodstream, and easily digestible simple carbs can result in glucose levels rising quickly.  

So, understanding how your glucose levels respond to different foods is key to keeping them steady. Read on to learn more about how individual responses vary and how you can understand your unique response.  

Tracking glucose levels with a CGM 

Even when considering the glycaemic index of foods and the glycaemic load (a metric calculated upon the quality and quantity of carbs in a food item or meal), individual responses can vary. 

With a continuous glucose monitor (CGM), you can learn your individual glucose response to meals and food choices, which can help you achieve more steady glucose.⁴ 

Lingo is a CGM that measures glucose levels in your interstitial fluid, the thin layer of fluid surrounding your body’s cells, and streams this data to your phone in real time. 

Knowing how your glucose responds to different foods can help you make better decisions about what you eat.⁵ 

For example, here are some questions that personal insights from a CGM may help you answer: 

• Should you opt for thin crust on family pizza night? 

• Which fruit and protein combo might work best as a mid-morning snack? 

• How big of a serving of rice should you have with your meal?  

• Should you eat a salad before your pasta? 

• Would swapping out fruit juice for some water or tea make a difference? 

• Should you plan to go for a stroll after eating a baked potato? 

Some research highlights how data from CGMs can help you make better nutrition choices based on your unique responses to food. Let’s look at one study published in the journal Nutrients that monitored healthy individuals wearing the Freestyle Libre CGM to track their glucose after eating different foods.¹ 

Individual glucose response findings with a CGM 

The study had 34 young, healthy volunteers (25 female, 9 male) wear CGMs for 14 days, which is the normal wear life of the biosensor. Participants completed an oral glucose tolerance test where they consumed 75 g of glucose and observed their glucose responses over 2 hours using CGM. 

About half of the subjects were classified as high responders to 75 g of glucose, while the remaining were categorised as low responders. This means the high responders had distinctly higher glucose levels after consuming the 75 g of glucose than the low responders.  

Over the two-week study period, participants consumed four different test meals: 

• A rice-based meal 

• A sandwich meal 

• A chicken salad 

• A fruit bowl 

The participants ate each one on a different day after an overnight fast and took CGM readings every 15 minutes for 2 hours following the test meals. The meals ranged from including 59 to 94 g of carbohydrates, making up between 45 and 92% of the meals’ total calories. 

Here are the key findings: 

• High responders’ glucose levels were nearly identical after consuming the rice-based meal as to the 75 g of glucose in the oral glucose tolerance test (41% of participants). 

• For the sandwich and chicken salad meals, 42% and 32% were identified as high responders. 

• Only 23.5% of subjects were classified as high responders to the fruit bowl. And, in both high and low responders, glucose decreased the fastest after the fruit bowl. 

• Both groups experienced peak glucose levels 45 minutes following meals. 

• High responders’ glucose had a higher peak and stayed elevated until 75 minutes after the meal before decreasing, especially after meals with higher carb contents (rice-based meal, sandwich). 

• Low responders’ glucose did not peak as high and decreased towards baseline after the peak 45-50 minutes after meals. 

These findings highlight just how much people’s glucose responses to foods can vary. Several factors contribute to the individual variations in how people's bodies respond to the same food, like age, fitness level, genetics, and even the microbes living in your gut.⁶ 

How personal CGM data can help your nutrition choices 

Knowing whether or not you have a high or low glucose response to certain foods could help you pick the foods and meals that are most likely to keep your glucose steady. 

For instance, meals that are lower in carbs (such as a chicken salad) can be better options for people who have a high response to carbohydrate-rich meals (such as a rice-based meal). 

And if you know that a meal is going to contain carbohydrate-rich components that lead to a big glucose response (like rice), you can plan to include sources of protein, healthy fat, or fibre to reduce their effects. 

Alongside your nutrition choices, using a CGM could also help you build and adhere to healthy habits. In one study, people using a CGM had improved glucose levels due to making healthier food choices, exercising more, and weight loss.⁷ 

For example, some people may find in their CGM data that going for a walk or other moderate exercise after eating a meal with carbs helps blunt a glucose spike compared with when they eat the same meal without any activity afterwards.  

Lingo is a biosensor and coaching app that can help you identify your individual response to food — especially meals with carbohydrates — by monitoring your glucose after you eat. You can learn which food choices and lifestyle habits could support steady glucose based on your own metabolism. 

A final note from Lingo 

Learning how your glucose levels respond when you eat certain foods can help you to build healthy habits to avoid or lessen glucose spikes. Also known as blood sugar spikes, these occur when there is a rapid increase in glucose levels in your bloodstream. This can happen due to consuming certain foods, stress, or intense exercise. 

It’s normal for your glucose levels to go up and down throughout the day, but regular and consistent spiking can have a negative impact on your health and wellbeing.³ Some research has associated consistently elevated glucose with an increased risk of developing type 2 diabetes and cardiovascular disease.^8,9 

Tracking your glucose with Lingo could help you to build healthy habits that support more steady glucose and your health goals. 

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