Here is an interesting article that was published in the Proceedings of the Royal Society of Medicine in 1949. It points out that type 2 diabetes is common in places where people eat a fatty, low-carb diet and rare in places where people eat a starchy, low-fat diet. When a population that had been eating a fatty diet switches to a starchy diet, such as under rationing in wartime, the number of people who die of complications of diabetes falls off dramatically. See the graph on page 324 to see the effects of rationing, economic slump, and the introduction of insulin therapy on the number of people who died of diabetes in England and Wales in the early 20th century.
The author pointed out that you can see the same relationship between high fat consumption and deaths from diabetes all over the world:
There thus seems to be a universal relation between diet and diabetic mortality. The dietetic factor most closely related is fat consumption.
It may seem odd that the introduction of insulin therapy didn’t make a dent in the graph. That’s because most people with diabetes have type 2 diabetes, which used to be called non–insulin-dependent diabetes. You’d see a different picture if you looked at a graph of deaths from type 1 diabetes, which used to be called insulin-dependent diabetes.
Note: For a clear explanation of why high-carbohydrate diets are good for people with any type of diabetes, see my book Thin Diabetes, Fat Diabetes: Prevent Type 2, Cure Type 2.