Vegan diet for diabetes: Tips, benefits and safety

Delve into our guide to a vegan diet for diabetes, including a look at the science behind how this eating pattern could manage – or even prevent – this condition

How effective is a vegan diet for diabetes prevention and management? Plant-based diets are increasingly being recognized as one of the healthiest and most sustainable dietary patterns. Given that they tend to be high in fiber and low in saturated fat, vegan diets have been widely studied for their preventative and therapeutic effects on high blood sugar levels.

So far, the results are promising. However, poorly planned plant-based diets may be high in carbohydrates and sodium – two nutrients that diabetics need to watch out for. Knowing how to structure a vegan diet is essential when it comes to successful prevention and management of this chronic disease.

Diabetes is a condition characterized by abnormally high blood glucose levels. In healthy individuals, the hormone insulin helps to deliver the glucose into the body's cells, providing them with essential fuel. In those with diabetes, the body doesn't produce enough insulin or doesn't use the insulin as it should. Over time, high blood sugar can cause heart disease, kidney problems, blindness and other complications. A healthy diet is one of the most important factors in helping to prevent and manage it.

Here, we discuss the benefits and downsides of a vegan diet for diabetes, as well as providing useful tips. However, it is still advised to consult your doctor before you introduce any changes to your diet, especially if you are diabetic.

According to the Vegan Society, a vegan diet excludes all animal-based foods. This includes:

Vegans tend to base their meals on fruits, vegetables, grains, pulses, nuts and seeds, and may need to use certain dietary supplements to avoid potential deficiencies.

Many features of vegan diets promote healthy blood sugar metabolism. "Because vegans have consciously made a choice to avoid certain foods, namely those of animal origin, they tend to pay more attention to what they eat to ensure they don't miss out on essential nutrients, and this results in them making better food choices," says James Collier, a registered nutritionist and co-founder of Huel.

After graduating with an Honours Degree in Nutrition with Dietetics from the University of Surrey, U.K. in 1995, Collier worked for seven years as a clinical dietitian for the National Health Service in various hospitals and various dietetic specialities. He is the co-founder and developer of Huel, nutritionally complete food.

"Many plant-based food choices are not only nutrient-packed, but also filling. For instance, fibrous wholegrains provide slow-release energy-efficient carbs, fiber and key vitamins and minerals. Plant-based diets are also rich in phytonutrients and these often have antioxidant benefits, which may help to protect against cardiovascular disease and some cancers."

On the other hand, common vegan staples like fruits, grains and pulses are high in carbohydrates. As stated in a review published in the Nutrition journal, restricting carbohydrates is one the safest and most effective ways of managing diabetes.

At the same time, scientists from the Nutrition Reviews journal suggest that when it comes to carbohydrate consumption and insulin response, quality is more important than quantity. Carbohydrate quality is usually measured with a glycemic index (GI): a rating system showing how quickly a particular food item can raise your blood sugar levels when it's eaten on its own. As such, eating moderate amounts of low-GI foods could be a good strategy for type 2 diabetics.

But which foods are considered low-GI? According to the GI tables published in The American Journal of Clinical Nutrition, pasta, legumes and many fruits tend to be most suitable. But some fruits are more sugary than others, so make sure to read our guide on which fruits are good for diabetics to make sure you pick the best ones.

Cereal products and baked goods show a wide variation in their GI values. Usually, less-processed, wholegrain products tend to be better for blood glucose management. Rice, savory snacks, sweets, potatoes and sugar-sweetened beverages are high-GI foods and it's best to avoid them.

Another important aspect is salt (sodium) intake. As described in the Journal of Human Hypertension, people with diabetes are sensitive to the negative health effects of excessive salt consumption. And as reported in the Clinical Nutrition journal, low-quality vegan diets may be high in this micronutrient. To make sure that you don't eat too much salt, limit your consumption of sodium-rich foods, such as processed baked goods, savory snacks, meat substitutes, canned goods and instant meals.

One of the potential benefits of a vegan diet for diabetes is improved weight management. Being overweight or obese is strongly linked to insulin resistance and type 2 diabetes. As stated in the British Medical Journal, maintaining a healthy weight is a core part of diabetes management. Losing weight helps to stabilize blood sugar levels, lower blood pressure and prevent cardiovascular problems.

Multiple studies have shown that plant-based diets tend to be more effective than omnivorous diets at achieving weight loss outcomes. Check out our guide on how to follow a vegan diet for weight loss to find out more.

According to a meta-analysis published in the JAMA Internal Medicine journal, higher adherence to this plant-based dietary pattern can significantly reduce the risk of developing type 2 diabetes. This link was strong with higher consumption of fruits, vegetables, whole grains and nuts.

A faulty pancreas is one of the root causes of type 2 diabetes. As described in the Journal of Population Therapeutics and Clinical Pharmacology, low-fat vegan diets may help to keep your pancreas in check. Obesity and dyslipidemia may disrupt the function of insulin-producing pancreatic cells, ultimately leading to their death. High blood glucose levels can speed up this process further. Diets high in animal-based saturated fats are particularly harmful, while plant-based unsaturated fats appear to protect pancreatic cells from damage.

Vegan diets may also be better than omnivorous diets at improving insulin sensitivity. According to a review published in the Clinical Nutrition ESPEN journal, animal protein intake intensifies insulin resistance, whereas plant-based foods enhance insulin sensitivity. This happens regardless of one's bodyweight.

A growing body of evidence suggests that vegan diets can be effective at managing existing type 2 diabetes. Multiple studies have demonstrated that plant-based diets are better at reducing HbA1c (glycated hemoglobin test, which measures changes to your blood sugar level over the last 2-3 months) than conventional diets. However, some healthcare providers argue that patients may find vegan diets hard to follow.

People with type 1 diabetes may need to be extra vigilant when planning their diet.

"For type 1 diabetes, it's important to balance the right amount of carbohydrates with the right amount of insulin and consider how different foods will impact your blood glucose levels," says Dr Tariq Mahmood, a gastroenterologist and medical director at Concepto Diagnostics. "This will still apply when adhering to a vegan diet, which is typically healthier than a modern diet.

"While eating fruits and drinking juices and smoothies is healthier than cakes and fizzy drinks, you should still be aware of the amount of carbohydrates being consumed. This is especially an issue when it comes to fruit, as juices and smoothies make it easy to consume a large portion in one sitting."

A vegan diet may be a useful tool for preventing and managing diabetes, but this approach may not be suitable for everyone. Plant-based diets need to be well-balanced. As such, they require more planning, preparation and surveillance than conventional diets. As suggested in the Nutrients journal, vegan diets may not be suitable for diabetes management in children, adolescents, frail elderly, and pregnant or breastfeeding women.

"All vegans should pay careful attention to their food choices, irrespective of whether they’re a diabetic," says Collier. "Although many of the foods in vegan diets are healthy, it doesn't necessarily mean that all vegan diets are healthy. There are plenty of vegan-suitable junk snacks that should only be consumed occasionally and in moderation."

Vegan diets may also be restrictive, particularly when adapted for patients with diabetes. It may be relatively easy to develop nutritional deficiencies and imbalances. Many foods with a medium-to-high carbohydrate content are great sources of dietary fiber, vitamin C, B vitamins, and health-promoting phytonutrients. Vegans may also struggle with obtaining enough calcium, iron, zinc, vitamin D, vitamin E or essential omega-3 fatty acids. Certain micronutrients, such as vitamin B12, are practically non-existent in plant foods and need to be supplemented.

"Beneficial omega-3 fats will have to be obtained from foods like flaxseed, walnuts, hemp seeds, chia seeds or algae-based foods or supplements," says Collier. "As plant-based diets also lack sufficient vitamin B12, a B12 supplement is advised. Many cereals and grains contain phytic acid which itself is a phytonutrient. Phytic acid is also an antinutrient. Antinutrients are substances which, while having health benefits themselves, can affect the bioavailability of other nutrients. Too much phytic acid can bind iron which is why vegans can be at greater risk of iron-deficiency anemia. Fortunately, nuts, seeds and leafy-green veg are rich in iron. Also, vitamin C promotes the uptake of iron helping to prevent iron deficiency."

You might ask, ‘do you need to eat meat to get protein?’. The answer is no, however, vegan diets will usually require more planning and preparation. This is because the quality of plant-based protein may not always be comparable to that found in animal-based foods.

Meat, dairy and eggs contain enough of all the essential amino acids – the building blocks of protein molecules that we are unable to produce ourselves. Most vegan sources of protein tend to lack one or more of these components. To make sure you get all the necessary amino acids, include more complete, or almost complete, plant-based protein sources in your diet. Other strategies are to ‘mix and match’ multiple incomplete protein sources, or invest in the best vegan protein powder to bridge potential gaps in your diet.

When balanced, plant protein can be beneficial for the management of diabetes. "High animal protein intakes have been associated with an increased risk of type 2 diabetes, while a moderate plant protein intake is associated with a decreased risk," says Mahmood. This claim is backed up by years of research. Multiple studies have demonstrated how substituting red and processed meat with plant-based protein helps with blood sugar level regulation.

This article is for informational purposes only and is not meant to offer medical advice.

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Anna Gora is a health writer at Live Science, having previously worked across Coach, Fit&Well, T3, TechRadar and Tom's Guide. She is a certified personal trainer, nutritionist and health coach with nearly 10 years of professional experience. Anna holds a Bachelor's degree in Nutrition from the Warsaw University of Life Sciences, a Master's degree in Nutrition, Physical Activity & Public Health from the University of Bristol, as well as various health coaching certificates. She is passionate about empowering people to live a healthy lifestyle and promoting the benefits of a plant-based diet.

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