For healthy diets with high plant content, such as fruits, vegetables, whole grains, beans and nuts, this protection is stronger.
Diabetes is called "the fastest growing health crisis of our time". At the same time, plant-based diet is becoming more and more popular.
Therefore, researchers think it is very important to quantify their relationship with diabetes risk, said Frank Qian, the first author of Harvard School of Public Health, especially considering that these diets are very different.
The analysis, published in the Journal of the American Medical Association, followed more than 300,000 participants for 2 to 28 years, of whom 23,544 had type 2 diabetes.
In the preliminary assessment, scientists observed that the total intake of plant food was high, and there was little or no animal food.
They found that the risk of type 2 diabetes was reduced by 23% compared with people who ate the least plant food.
However, these dietary patterns do not exclude plant-derived foods, such as sugar and refined carbohydrates, which are related to the high risk of diabetes.
When the analysis was narrowed down to four vegetal diets, they found that the risk of type 2 diabetes was reduced by 30%.
Although it must be pointed out that these studies are observational, they are all adjusted according to well-known risk factors, including body mass index (BMI), gender, smoking status and family history of diabetes, and other variables that may be confused.
Researchers say there are several factors that can explain these connections.
Plant-based diet usually includes healthy plant-based food, which contains nutrients, polyphenols and fiber, which can improve insulin sensitivity, lower blood pressure, reduce inflammation and help maintain a healthy weight.
All these can reduce the risk of type 2 diabetes. On the contrary, eating red meat and processed meat is associated with higher risk.
"Overall, these data emphasize the importance of adhering to a plant-based diet to achieve or maintain health," Qian said.