"Vegetable diet will beat diabetes: Meat-free lifestyle cures killer disease," is the typically overblown headline in the Daily Express.
But researchers actually found a vegetarian diet led to a quite modest fall in only one measure of blood glucose called HbA1C, a measure of blood glucose control.
The paper reports on a systematic review which combined the results of six trials that involved 255 people with type 2 diabetes. They examined whether vegetarian or vegan diets improved blood glucose control compared with a control diet.
Overall, the pooled results of five of these trials found a vegetarian or vegan diet reduced HbA1c by 0.39%. There was no significant effect on fasting glucose levels, an assessment of how efficiently the body can process glucose in the short term.
This slight reduction in HbA1c is no cure. As the researchers themselves pointed out, the reduction is less than you would expect if a patient was being treated with the drug of choice for type 2 diabetes, metformin.
This review also has various important limitations, including the variable design and quality of the six trials included. So, it does not prove that a vegetarian or vegan diet is better for a person with type 2 diabetes, and any media claims of a "cure" for the condition are entirely baseless