Type 2 diabetes has become one of America’s fastest growing health crises. Each year, about 1.5 million people are newly diagnosed with diabetes, and of the total of 30.3 million Americans with the disease, most of them with type 2 diabetes, an estimated 7.2 million are undiagnosed, according to the American Diabetes Association.

But a large study has found that eating more whole grains of any type may cut the risk of developing this condition, which causes hyperglycemia, or high blood sugar, and can increase the risk of life-threatening complications such as heart disease, neuropathy, and kidney damage.

The research, published in the September 2018 issue of the Journal of Nutrition, involved more than 55,000 individuals, and suggests that increased intake of whole-grain wheat, oats, and rye may help reduce a person's risk for type 2 diabetes.

“High whole-grain intake is important for lowering of type 2 diabetes risk, and we found that it can come from a range of different whole grains,” says the study's senior author, Rikard Landberg, PhD, the head of the division of food and nutrition at Chalmers University of Technology in Gothenburg, Sweden.

While there are multiple factors that may contribute to diabetes risk, including genetics, diet choices appear to play a role, according to the Mayo Clinic.

Many Types of Grains May Help Protect Against Diabetes

Investigators observed that wheat, rye, and oats were associated with a lower risk of diabetes in men, while wheat and oats were linked with a lower risk of the disease in women.

Dr. Landberg says that many similar studies have been conducted in the United States, where people mainly get their whole grains from wheat. Participants in this study (all from Denmark) got their whole-grain intake from many sources, including muesli, hot oatmeal, and rye bread.

Over 15 years, the authors followed 55,465 participants, who at the beginning of the study were ages 55 to 65 and did not have diabetes. Of these, 7,417 participants were diagnosed with type 2 diabetes during follow-up.

Researchers divided the subjects into four groups who ate different daily amounts of whole grains. The lowest 25 percent were eating less than 27 grams (g) per day, and the top 25 percent were eating at least 50 g per day.

Men in the group who ate the most whole grains had a 34 percent lower risk of getting diabetes compared with those who ate the least. For women in the high-intake group, diabetes risk was 22 percent lower.

To Reap the Benefits of Whole Grains, Be Sure to Check Food Labels

Jan Rystrom, RD, a certified diabetes educator with Swedish Diabetes Education and Nutrition in Seattle, Washington, says the results add to a growing body of research showing that high fiber intake correlates to lower diabetes risk.

Rystrom often encourages her patients to increase their whole-grain consumption but warns them to read the packaging carefully.

“In the U.S., what is used in most commercially processed grain products, labeled whole grain breads and cereals, is technically not a whole grain but a processed grain,” says Rystrom. “I teach patients to look for the Whole Grains Council stamp on the package that shows 100 percent whole grain as compared with a label that might just show “whole grain,” which can be a mix of whole and refined grains.”

Minisha Sood, MD, an endocrinologist affiliated with Lenox Hill Hospital in New York City, warns against eating refined flour such as all-purpose flour that is often used in white bread, bagels, waffles, and pancakes. Carbohydrate metabolism is a factor in the development of type 2 diabetes. Refined flour has a high glycemic index, meaning it is more quickly digested, metabolized and absorbed, causing spikes in blood glucose levels. Dr. Sood says that American consumers also eat way too many snack foods and fast foods, which are sorely lacking in whole grains.

“One really needs to be able to take the time to shop for whole grains and prepare foods at home,” says Audrey Koltun, RD, a certified diabetes educator with Cohen Children’s Medical Center in New Hyde Park, New York.

She adds that readers should not walk away thinking that eating whole grains is all they need to do diet-wise to prevent type 2 diabetes. “It is important to incorporate whole grains but also eat vegetables, fruits, lean or plant-based proteins, and healthy fats,” says Koltun.

Why Might Whole Grains Help Prevent Type 2 Diabetes?

Because they are high in fiber and complex carbohydrates, whole grains do not break down as rapidly as refined grains in the digestive tract, and so they do not raise the blood sugar as dramatically, Rystrom says.

High-fiber diets have also been correlated to lower body weight, and lower body weight helps prevent type 2 diabetes, says Rystrom. This correlation was shown in a study published in February 2015 in the Annals of Internal Medicine.

Dr. Landberg says the dietary fiber can have a positive effect on inflammation and body fats as well. “Moreover, dietary fiber is a good energy source for gut microbiota [microorganisms], and in particular the microbiota which has been associated with health,” he says.

How to Increase Your Fiber and Whole-Grain Intake

Koltun says one of the limitations of the study was that it focused on rye bread, whole grain bread, and oatmeal/muesli, but did not mention other choices.

In addition to the whole grains mentioned, she recommends these whole grains for her patients with diabetes:

Quinoa (which is gluten free)
Teff
Bulgur
Millet
Buckwheat
Amaranth (gluten free)
Brown rice (gluten free)
Farro

Rystrom encourages her patients to make healthy whole-grain swaps when they can. For example, try trading your white pasta for the whole-grain variety, or cooking quinoa or bulgur instead of white rice. And your options aren’t limited only to whole grains — foods like legumes, beans, nuts, and seeds are also rich in fiber, and may also help reduce your risk for diabetes.

“I encourage everyone to consider eating more fiber and strive for a fiber minimum of 35 grams per day from a variety of sources, including legumes, vegetables, and 100 percent whole grains,” says Rystrom.