Excess weight is a major risk factor for type 2 diabetes. Recent research, however, suggests one strategy that could help to prevent the condition in people who are overweight, and it involves giving up meat and dairy.

Researchers found that overweight people who switched to a vegan diet for 16 weeks showed improvements in insulin sensitivity plus the functioning of beta cells, compared with a control group.

Beta cells reside in the pancreas and produce and release insulin.

The vegan diet also led to improvements in blood sugar levels, both during fasting and during meals.

Lead study author Dr. Hana Kahleova, of the Physicians Committee for Responsible Medicine in Washington, DC, says that the findings have "important implications for diabetes prevention."

Dr. Kahleova and colleagues recently reported their results in the journal Nutrients.

Type 2 diabetes arises when the body is no longer able to respond to insulin effectively—which is a condition known as insulin resistance—or the pancreatic beta cells do not produce enough insulin. Insulin is the hormone that regulates blood sugar levels.

As a result of this, blood sugar levels can become too high. This can lead to serious complications, including cardiovascular disease, kidney disease, diabetic eye disease, and nerve damage.

It is estimated that more than 30 million people in the United States are living with diabetes, and type 2 diabetes accounts for around 90%–95% of all cases.

Studying the effects of a vegan diet

Being overweight is one of the leading risk factors for type 2 diabetes. In fact, around 80% of people who have type 2 diabetes are overweight or obese.

Making lifestyle changes—such as adopting a healthful diet and increasing physical activity—can help to reduce the risk of type 2 diabetes. The new study from Dr. Kahleova and her team provides further evidence of this, after identifying a vegan diet as a possible candidate for the prevention of type 2 diabetes in people who are overweight.

To reach their findings, the researchers enrolled 75 men and women between the ages of 25 and 75 years. All participants had a BMI of between 28 and 40, making them overweight or obese, but they had no history of diabetes.

For a total of 16 weeks, subjects were randomized on a 1:1 ratio to two different groups. One group followed a low-fat vegan diet, which consisted of fruits, vegetables, legumes, and grains. This diet had no calorie restriction. Participants in the other group (the controls) were asked to make no changes to their diet.

The team notes that neither group made any changes to their physical activity, nor did they change their use of medications.

Beta cell function, insulin sensitivity, blood glucose levels, and the BMI of each subject were assessed at study baseline and at the end of the 16 weeks.

'Food really is medicine'

The study results revealed that the participants who followed the low-fat vegan diet experienced a significant reduction in BMI, compared with the control group.

What's more, the vegan group experienced increases in insulin secretion after eating, as well as improvements in insulin sensitivity.

Subjects who adhered to the vegan diet also experienced reductions in blood sugar levels during meals and while fasting.

Based on these results, the team suggests that adopting a vegan diet could be an effective way to prevent type 2 diabetes.

"If nothing changes, our next generation—the first expected to live shorter lives than their parents—is in trouble. A third of young Americans are projected to develop diabetes in their lifetimes," says Dr. Kahleova.

"Fortunately, this study adds to the growing evidence that food really is medicine and that eating a healthful plant-based diet can go a long way in preventing diabetes."

Dr. Hana Kahleova

The researchers note some important limitations to their study. For example, they point out that the study subjects were "generally health-conscious individuals" who were willing to make significant dietary changes.

"In this regard, they may not be representative of the general population," say the authors, "but may be representative of a clinical population seeking help for weight problems."

Still, the results certainly warrant further investigation.