Diabetes: can changing your diet help prevent and treat it?
Type 2 diabetes is one of the fastest-growing health problems in the world. But our risk is not simply written into our genes. What we eat can make a profound difference – both to preventing the disease and to managing it once it develops.
Diabetes is often thought of as a disease caused by eating too much sugar. The reality is considerably more complex.
Diabetes occurs when glucose builds up in the bloodstream instead of being moved efficiently into the body’s cells. Over time, persistently high blood glucose can damage blood vessels and organs, increasing the risk of complications affecting the heart, kidneys, eyes and nerves.
The encouraging news is that, particularly with type 2 diabetes, diet and lifestyle can have a powerful influence on the underlying metabolic problems.
Viva!’s approach is straightforward: build the diet around whole plant foods, increase fibre, reduce saturated fat and highly processed foods, and choose carbohydrates that release their energy more slowly.
Understanding diabetes
There are several forms of diabetes.
- Type 1 diabetes is an autoimmune condition in which the body’s immune system destroys the insulin-producing cells of the pancreas. People with type 1 diabetes need insulin replacement.
- Type 2 diabetes is much more common, accounting for around 90 per cent of cases. It develops when the body becomes resistant to insulin, does not produce enough insulin, or both.
There is also gestational diabetes, which can develop during pregnancy, as well as several rarer forms.
Insulin is a hormone that helps glucose move from the bloodstream into cells, where it can be used for energy. When insulin is not working effectively, glucose remains in the blood instead.
Symptoms of diabetes can include excessive thirst, frequent urination – particularly at night – tiredness, unexplained weight loss, blurred vision, genital itching or thrush, and cuts or wounds that heal slowly.
But type 2 diabetes can develop gradually, and some people may have few obvious symptoms. That makes prevention and early intervention particularly important.
It’s not just about sugar
If sugar isn’t the whole story, what is?
One of the key problems in type 2 diabetes is insulin resistance. In simple terms, the body’s cells stop responding properly to insulin.
This may be the result of excess fat stored inside cells, particularly in the liver and muscles which can interfere with insulin’s ability to do its job, contributing to rising blood glucose levels.
This is one reason why simply telling people to “eat less sugar” misses an important part of the picture. The overall composition of the diet matters.
Diets high in animal fat, meat and processed foods can contribute to a dietary pattern associated with insulin resistance, while diets centred on whole plant foods provide considerably more fibre and are generally lower in saturated fat.
And while carrying excess body weight increases the risk of type 2 diabetes, insulin resistance is not exclusively a problem for people who are visibly overweight. Metabolic health can be affected even when someone’s weight appears normal.
The plant-based advantage
So, what should we eat?
The answer is fairly simple; a wholefood, plant-based diet built around vegetables, fruit, wholegrains, beans, peas, lentils, chickpeas, soya, nuts and seeds.
These foods provide an abundance of fibre, vitamins, minerals and plant compounds while supplying carbohydrate in a form that is absorbed into the body much slower than the refined carbohydrates found in many highly processed foods that cause sugar spikes.
Fibre is particularly important.
Unlike refined carbohydrates, fibre is not rapidly broken down and absorbed as glucose. Fibre-rich foods can help slow the release of carbohydrates, support digestive health and make meals feel substantially more filling.
Plant foods also contain phytochemicals – naturally occurring compounds found in plants – which may contribute to the beneficial effects associated with diets rich in fruit and vegetables.
Three principles for better blood glucose control
1. Make whole plant foods the foundation
Think of the plate as being built around plants rather than treating vegetables as a side dish.
Good choices include:
- Oats and other wholegrains
- Brown rice and quinoa
- Wholemeal and rye breads
- Beans and lentils
- Chickpeas and peas
- Tofu and other soya foods
- A wide variety of vegetables
- Whole fruit
- Nuts and seeds
A diet based on these foods also naturally reduces reliance on meat, dairy and other animal products, which are significant sources of saturated fat and dietary cholesterol.
The relationship between diabetes and kidney health is also important to consider, particularly in relation to dietary protein and existing kidney damage.
2. Keep dietary fat under control
Not all fat is the same, focus on reducing total dietary fat and saturated fat.
The reasoning is linked to the role of fat accumulation inside cells and its relationship with insulin resistance.
That doesn’t mean eliminating fat altogether. Essential fatty acids are necessary for health.
Plant sources of healthy omega-3 fats include:
- Ground flaxseed
- Chia seeds
- Hemp seeds
- Walnuts
Incorporate small amounts of these foods regularly while avoiding excessive amounts of added oils and other high-fat foods.
3. Choose lower-GI carbohydrates.
Carbohydrate has sometimes been unfairly blamed for diabetes. The type and quality of carbohydrate matter enormously.
The glycaemic index (GI) is a measure of how quickly carbohydrate-containing foods raise blood glucose.
Low-GI foods tend to release their carbohydrate more gradually, while high-GI foods can cause a faster rise in blood glucose.
Low-GI choices include:
- Beans, lentils, chickpeas and soya
- Most vegetables
- Many fruits
- Hummus
- Pasta
- Nuts and seeds
- Sweet potatoes
- Jumbo oats
- All-Bran-type cereals
- Wholegrain pumpernickel bread
- Soya yoghurt
Medium-GI choices include foods such as wholemeal and rye bread, brown and basmati rice, quinoa, porridge oats, shredded wheat, pineapple, melon, figs and raisins.
Highly refined foods such as white bread, white rice, rice cakes and many sugary breakfast cereals are higher-GI choices and are best kept to a minimum.
The message isn’t avoid carbs, it’s choose better carbs.
What about fruit?
Fruit contains naturally occurring sugars, but whole fruit also comes packaged with fibre, water, vitamins, minerals and plant compounds.
This makes whole fruit very different from foods and drinks containing large amounts of added sugar.
The emphasis should therefore be on eating fruit in its whole form rather than assuming that all sources of sugar have the same effect on the body.
Weight matters – but so does what you eat
Excess body weight is an important risk factor for type 2 diabetes and losing weight can improve metabolic health.
But the approach is not based simply on counting calories or eating tiny portions.
Whole plant foods are generally rich in fibre and water and relatively low in energy density. They can therefore provide satisfying portions without the same calorie load as many high-fat or highly processed foods.
There is an important point about nuts and seeds: although they are nutritious and can be part of a diet that helps reduce the risk of type 2 diabetes, they are also energy dense. Portion size therefore matters, particularly if you’re trying to manage your weight. You can eat nuts and seeds regularly, but a moderate portion – around a small handful (about 30 grams) – is a useful guide and opt for unsalted as the healthier option.
For some people, adopting a low-fat wholefood plant-based diet can result in significant weight loss without the need for severe calorie restriction.
Can type 2 diabetes actually be reversed?
This is where the subject becomes particularly interesting.
Type 2 diabetes can sometimes go into remission, particularly when substantial improvements are made to diet, weight and metabolic health.
A number of studies have shown how people with type 2 diabetes made dietary and lifestyle changes and experienced major improvements in blood glucose control, sometimes allowing their medication requirements to fall.
However, medication should never be reduced or stopped without medical supervision. Dietary changes can alter blood glucose levels significantly and anyone taking diabetes medication needs appropriate monitoring.
The important point is that a diagnosis of type 2 diabetes does not necessarily mean that health can only deteriorate from that point onwards. Metabolic health can change – and, in many people, it can change dramatically.
The importance of vitamin B12
Anyone following a vegan diet needs a reliable source of vitamin B12.
This can come from a supplement or fortified foods. Viva! recommends regular B12 supplementation and also highlights the importance of paying attention to B12 status in people taking metformin, a commonly prescribed diabetes medication.
Vitamin D may also require supplementation, particularly during the winter months in the UK – this applies to everyone in the UK, regardless of diet.
These nutrients are important reminders that a healthy plant-based diet isn’t simply about removing animal products. It is about making sure your diet is nutritionally complete.
Food and exercise work together
Diet is only one piece of the puzzle.
Regular physical activity can complement dietary changes by helping with weight management and metabolic health. Combining dietary improvements with exercise can lead to substantial improvements in people with type 2 diabetes.
You don’t necessarily need an extreme exercise programme. Building more movement into everyday life – walking, cycling, gardening, active hobbies or structured exercise – can all contribute to a healthier lifestyle.
A simple way to think about your plate
Rather than concentrating on individual nutrients, think about the overall pattern of your meals.
Build meals around:
Fruit and vegetables + wholegrains + pulses + modest amounts of nuts and seeds
For example, breakfast could be porridge with fruit and ground flaxseed. Lunch might be a large salad or vegetable bowl with chickpeas and wholegrains. Dinner could centre on lentils, beans or tofu with plenty of vegetables and brown rice or another wholegrain.
The exact foods matter less than the pattern.
The more often meals are built from minimally processed plant foods, the easier it becomes to crowd out foods that are high in saturated fat, refined carbohydrate, added sugar and excess calories.
The bigger picture
Diabetes is not simply a story about sugar.
It is a story about how the body handles energy, insulin and glucose – and how those processes are influenced by the food we eat, our weight, our activity levels and our overall lifestyle.
The approach outlined is therefore not a crash diet or a short-term prescription. It is a fundamental shift towards a balanced diet dominated by whole plant foods.
That means more vegetables, fruit, beans, lentils, wholegrains and other fibre-rich foods; less saturated fat and highly processed food; careful use of added fats; and regular sources of essential nutrients such as vitamins B12 and D.
For people who have not developed type 2 diabetes, such a dietary pattern may help reduce their risk.
For those who already have the condition, improving diet and lifestyle can form an important part of managing blood glucose and reducing the risk of complications.
And perhaps most importantly, the message is one of possibility rather than inevitability.
A diagnosis of type 2 diabetes does not have to be the end of the story. Changing what we put on our plates can be one of the most powerful steps we take towards changing what happens inside our bodies.
Thanks to Veronika Prošek Charvátová MSc for additional research.
This feature is intended as health information rather than individual medical advice. Anyone with diabetes, particularly anyone taking glucose-lowering medication, should discuss significant dietary changes with their healthcare professional.
About the author
Dr. Justine Butler
Justine joined Viva! in 2005 after graduating from Bristol University with a PhD in molecular biology. After working as a campaigner, then researcher and writer, she is now Viva!’s head of research and her work focuses on animals, the environment and health. Justine’s scientific training helps her research and write both in-depth scientific reports, such as White Lies and the Meat Report, as well as easy-to-read factsheets and myth-busting articles for consumer magazines and updates on the latest research. Justine also recently wrote the Vegan for the Planet guide for Viva!’s Vegan Now campaign.
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