Mark Green Libre Connect 2024 -
Summary Blog

By Mark Green

Disclaimer: The information provided is not intended to be used for medical diagnosis or treatment. Please consult your healthcare professional about your diabetes management. Individual symptoms, situations and circumstances may vary.

13/02/2025

Understanding the impact of different foods on blood glucose levels

We kicked off with a bit of science, as many people living with diabetes are confused by the terms “glycaemic index (GI)” and “glycaemic load (GL)”. So, what’s the difference?

In short, GI measures how quickly carbohydrate-containing foods affect blood glucose levels, with high GI foods having more potential to cause rapid spikes and low GI foods resulting in slower increases. Foods like white bread and mashed potatoes are high GI, while whole grains and legumes are lower GI. 

A useful analogy is to think of high GI like a ‘waterfall’ which your body can struggle to keep up with at times, where more glucose is absorbed at one time. Whereas low GI is more of a ‘drip effect’, where glucose is steadily absorbed in a slower pace, so your body is more easily able to deal with those glucose rises.

Glycaemic index is important, but it can only take you so far. Glycaemic load is my preferred measure, because it has a larger effect on blood glucose levels. GL considers both the amount of carbohydrates and how quickly they’re absorbed, i.e. the ‘load’ being placed on your bloodstream. Foods that generally get a bad name in diabetes such as sugary foods will have a high GL, whereas those with a low GL are things like veggies, fruit, and legumes.

Portion size, cooking methods and food preparation all play a part too

Therefore, a common issue is focusing only on switching from high to low GI foods without realising that portion size (GL) also plays a significant role. Even if food has a low GI, consuming it in large amounts can still lead to blood glucose spikes.

For example, if we take a watermelon (high GI) vs. chocolate (medium GI), while chocolate may seem like a better option based on GI alone, the total carbohydrate content (GL) in chocolate is higher. Therefore, chocolate is more likely to raise your glucose levels more easily than watermelon, despite the fact, watermelon has a higher GI.

Think of the portion as the dominant factor, with the GI as another tool in your toolbox. 

The way in which food is prepared can also influence glucose spikes. For example, mashing or juicing increases the glycaemic impact because it breaks down starches and sugars, making them more readily absorbable. A good tip here is to choose foods where your body has to do the work, so go for wholefoods where possible.

Equally, serving pasta al dente instead of overcooking it can help to better manage post-meal glucose levels by making it slower to digest.

Debunking myths around food choices

A popular myth is that “you can eat whatever you want as long as you inject insulin for it”. Though accurate insulin dosing can manage blood glucose, healthy eating patterns and portion control are still essential for long-term health. Whole grains, fruit, and veg (‘5 a day’ minimum), lean proteins and healthy fats should be the foundation of a diabetes-friendly diet, or any diet for general health. 

It’s just as important to dispel misconceptions about certain foods (e.g. nuts consumed in moderation being fattening) and to promote the inclusion of healthy fats like oily fish, olive oil, peanut butter or avocado in moderation, which can slow glucose absorption and provide essential nutrients. No food is off limits but foods high in fat and sugar can more easily make you gain weight or increase glucose levels and so should be consumed in moderation. 

Enhancing enjoyment while managing diabetes

Food is a central part of our lives, so the social and psychological aspects of eating shouldn’t be overlooked either. Diabetes management doesn't mean giving up your favourite foods. It’s about making informed choices that help us enjoy the foods we love while maintaining our health.

It's possible to enjoy your favourite foods by making small adjustments, such as choosing low fat options, reducing portions or timing carbohydrate intake with protein or fats to slow glucose absorption.

In addition, simple ingredient swaps can reduce glucose spikes while still giving you flavoursome meals. For example, substituting white bread, butter, and jam with granary toast and peanut butter or incorporating more vegetables into meals (e.g. adding lentils to a stew or curry). Likewise, alternatives like using 50:50 brown and white rice, mixing courgetti with pasta, or replacing cereal with porridge or overnight oats can help lower the glycaemic impact.

Practising cooking skills and experimenting with new recipes can also help maintain a positive relationship with food while managing diabetes. And allowing for occasional indulgences, like having dessert while balancing the meal with healthier options, can make dietary changes sustainable and enjoyable.

The importance of mindful eating and timing

Eating slowly, mindfully, and allowing time for hunger hormones to catch up can prevent overeating and help manage blood glucose more effectively. Some simple strategies include putting down cutlery between bites or taking drinks/breaks during meals.

Timing meals consistently throughout the day and eating smaller, more frequent portions can also help stabilise blood glucose levels.

Mindful eating extends to restaurants or other types of eating out as well. Choosing smaller portions, being selective with high-carb sides and enjoying the social aspect can help maintain glucose control without sacrificing enjoyment.

The value of continuous glucose monitors (CGMs)

By providing real-time data, CGMs such as the FreeStyle Libre systems empower individuals to understand how specific foods and portion sizes affect their glucose levels. This feedback allows for informed decision-making and reduces anxiety around eating, thus enhancing enjoyment of food.

Both the panellists living with type 1 and type 2 diabetes reported that using CGMs helps them make healthier choices and feel more in control of their glucose management.