What Do You Eat to Reduce Your Risk for Diabetes?

Type 2 diabetes is among the most common chronic diseases in the US. Researchers believe that three fourths of the cases of type 2 diabetes could be prevented with lifestyle modifications. Chinese researchers recently studied high-fiber supplements for newly-diagnosed diabetes patients. Earlier, an analysis of dietary data from American health care professionals suggested ways to lower your risk for diabetes. In addition, researchers utilized the extensive data available through the UK Biobank to address the same question. To improve your odds of metabolic health, you must change your dietary habits to a more plant-based pattern with a focus on fiber.

What Does a High-Fiber Diet Do for Diabetes?

In a recent study, researchers recruited 48 heavy people who had just been diagnosed with type 2 diabetes (Frontiers in Microbiology, Oct. 1, 2026). They assigned some of them to a high-fiber diet and others to receive metformin, a common diabetes medication. None received other medications to lower blood sugar.

Over the course of nearly three months, people in the high-fiber group received either of two standardized high-fiber products. One contained wheat, oat and barley fiber, resistant dextrin, inulin, oligosaccharides and konjac gum. This provided both soluble and insoluble fiber. The other fiber supplement included these ingredients without the wheat, barley or oat fiber or konjac. Consequently, it offered predominantly soluble fiber. Investigators also encouraged the volunteers to eat plenty of vegetables, soy, algae, fruit and mushrooms. The participants kept records of their diet using food frequency questionnaires and 24-hour food recall.

Researchers measured gut microbe diversity and production of short chain fatty acids periodically throughout the trial. In addition, they collected information on insulin resistance, blood glucose (with CGMs) and HbA1c. They also conducted clinical assessments at baseline and at 28, 56 and 84 days of the study. (Day 84 was the final one of this protocol.)

How Well Did Fiber Work?

At the end of the study, those in the high-fiber group had lost more weight, possibly because the fiber supplements displaced more caloric foods. As a result, their BMI had decreased more than those in the metformin group. People in the fiber group had significantly lower HbA1c (6.32) than those on metformin (6.74). Average HbA1c at the outset was just under 7.5 in both groups. In addition, the balance of gut microbes had changed, with people in the high-fiber group hosting more beneficial Bifidobacterium and Lactobacillus gut microbes. The analysis also showed that by the end of the study, the gut microbes from people on the high-fiber diet were less likely to produce hydrogen sulfide (H2S). This is the gas that makes farts smelly. Note, the scientists did not actually measure intestinal gas production. They were looking solely at the genes from the microbes. These also indicated greater capacity for producing short-chain fatty acids (SCFAs).

The investigators noted,

“The high-fiber intervention improved both glycemic control and adiposity in participants with diabesity in our study.”

Because the treatment they tested was for people who had already been diagnosed with diabetes, it can’t tell us if a high-fiber diet can reduce the risk for diabetes. Other studies suggest it may.

Following a Plant-Based Diet Reduces the Chance of Type 2 Diabetes

An analysis a few years ago compared biomarkers and behavior among 113,000 participants in the UK Biobank study. This observational study lasted twelve years and included genetic data (Diabetes & Metabolism, Nov. 28, 2023). Researchers also analyzed markers of liver and kidney function, metabolism, inflammation and blood lipids. People following a healthful plant-based diet with little or no ultra-processed or highly sweetened foods were 24 percent less likely to develop type 2 diabetes during that time as people who ate a more conventional Western style diet. The healthy plant-based eating pattern contained lots of fresh vegetables, fruits and whole grains. People who consumed more sweets, sugary drinks and refined grains actually had an increased risk for diabetes even if their diets were mostly plant-based.

Which Dietary Patterns Have a Lower Risk for Diabetes?

In earlier research, scientists analyzed data from more than 200,000 participants in long-running observational studies (ASN 2020 Annual Meeting online). More than 150,000 women volunteered their data in the Nurses’ Health Study and Nurses’ Health Study 2. In addition, over 40,000 men participated in the Health Professionals Follow-up Study. All of these volunteers provided their dietary data every few years for decades.

Diabetes researchers have long suspected that high total carbohydrate intake could increase the risk for diabetes in adulthood. That is type 2 diabetes, controlled without insulin injections. These data show, however, that the picture is more nuanced. According to the research definitions, high-quality carbohydrates come from whole grains. On the other hand, low-quality carbohydrates are found in potatoes, sugary foods and beverages and refined grains.

If people ate high quality carbs instead of fats and animal protein, they had a lower risk for diabetes. People who consumed refined grains in the place of saturated fat were more likely to be diagnosed with type 2 diabetes.

Learn More

Even experts can’t tell how diet affects the risk for diabetes by simply adding up fats, proteins and carbohydrates. You have to look at the foods providing those macronutrients. In general, less-processed foods appear to be healthier.

You can learn more about diabetes from our interview with Yale professor Kasia Lipska, MD. It is Show 1173: How Is Diabetes Diagnosed and Treated?

More recently, we interviewed Dr. John Buse. He appeared in Show 1453: From Lizard Spit to Ozempic: Rethinking How We Treat Diabetes.

We also summarize research on type 2 diabetes in our eGuide to Preventing & Treating Diabetes.

You may also be interested in a study undertaken by Richard Bernstein, MD. He recommends relying on non-starchy vegetables like asparagus, beet greens, bell peppers, broccoli, cabbage and spinach. He has found that even whole grains raise blood sugar unacceptably. Although Dr. Bernstein includes meat, fish, fowl and eggs in his recommendations, other research suggests plant-based protein is superior. A meta-analysis of nine studies found that people consuming mostly vegetables, fruits, legumes, nuts and whole grains had a 23 percent lower risk for diabetes (JAMA Internal Medicine, July 22, 2019).

Mediterranean Diet Against Diabetes

Italian researchers found that people sticking close to a traditional Mediterranean diet had better blood sugar control (Nutrients, Aug. 10, 2018). They chose whole grains, beans, lentils, fruits, vegetables, nuts, fish and olive oil over processed foods and went light on meat, sweets and dairy products. As a consequence, they consumed more fiber and less energy (calories), calcium and sodium. Such individuals also ended up with more polyphenols in their food choices.