Updated 18th September 2025
Fiber and type 2 diabetes: What’s the link?
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Decades of research show that consuming adequate amounts of fiber is associated with good health.
However, shockingly, less than 1 in 10 people in the United States and the United Kingdom eat the recommended 30 grams per day.
Although we lack the enzymes to digest fiber, gut bacteria can digest it. This is one of the reasons why fiber is essential for good health:
It feeds your “good” gut bacteria and, as they ferment the fiber, they produce a range of compounds that support your overall health.
We’ve covered many of fiber’s health benefits before, but today, we’ll zero in on one particular aspect.
We’ll investigate whether consuming adequate fiber reduces your risk of developing type 2 diabetes.
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Fiber and type 2 diabetes risk: The evidence
In general, studies show that people who consume adequate fiber have a 20–30% reduced risk of developing type 2 diabetes compared with those who don’t consume enough.
In particular, the fiber found in wholegrains seems most effective, which includes:
Wheat: Whole wheat, quinoa, and bulgur.
Corn: Corn and popcorn.
Rice: Brown or wild rice.
Oats: Oatmeal.
Buckwheat.
Barley.
With fiber, at least up to a point, the more you have, the more it reduces your risk.
For instance, the authors of one review calculated that each 2-gram increase of fiber per day is associated with a 6% reduction in type 2 diabetes risk.
So, by making some simple swaps, you could start reducing your risk today. Here are some examples:
Swap white bread for wholemeal bread (choose a loaf containing seeds for extra fiber).
Swap white pasta for wholewheat or pasta made with legumes or spelt.
Swap white rice for brown rice or barley.
Swap white flour in baking for spelt, chickpea, or rye flour.
How does fiber reduce risk?
Precisely why fiber intake is associated with reduced type 2 diabetes is not fully understood, but it’s likely that there are multiple mechanisms, such as:
A high-fiber diet tends to be associated with lower levels of body fat, which itself reduces diabetes risk.
As some forms of fiber are fermented by gut bacteria, they produce short-chain fatty acids (SCFAs), which can support metabolic health.
Some forms of fiber slow the movement of glucose from your gut into your blood, so you are less likely to experience pronounced blood sugar responses.
High-fiber diets are linked to a reduction in inflammation, which may help reduce diabetes risk.
Can fiber help manage type 2 diabetes?
As we’ve seen, there’s good evidence that a high-fiber diet is associated with a reduced risk of developing type 2 diabetes. But can this approach help people who already have diabetes?
In 2020, a review and meta-analysis published in PLOS Medicine explored this question.
The authors collected data from more than 40 studies, including more than 10,000 participants with type 1, type 2, gestational, or prediabetes.
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Overall, they found that high-fiber diets were linked to better blood glucose control and healthier levels of blood fats.
They were also associated with lower body weight, reduced inflammation, and a reduced risk of premature death.
The authors conclude:
“Based on these findings, increasing daily fiber intake by 15 grams or to 35 grams might be a reasonable target that would be expected to reduce risk of premature mortality in adults with diabetes.”
How can you track how much fiber you eat?
The evidence is strong that a high-fiber diet can reduce your risk of developing type 2 diabetes and help manage diabetes.
As we mentioned, all plants contain fiber, and you should aim for at least 30 grams per day from a variety of different plants. If you focus on consuming 30 different plants per week, you are likely to hit your target.
But how can you keep track to make sure? Unless you carry around weighing scales and a calculator, tracking precisely how much fiber you eat each day is challenging.
Thankfully, ZOE's new app makes this easy. Simply snap a photo of a food product or a whole meal, and it provides nutritional information, including levels of fiber, carbs, and protein.
The app also tells you whether products have any risky additives or processing you should be aware of. Download it here.
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Summary
Consuming adequate fiber is associated with a wide range of health benefits, including a reduced risk of developing type 2 diabetes.
The best way to get more fiber into your diet is by upping your plant intake and focusing on plant diversity.
Aim for 30 different plants per week, which can include fruits, veggies, pulses, beans, nuts and seeds, and herbs and spices.
And the best way to track how much fiber you’re consuming is to download our app today.
