Just read this article and will have to review the medical literature.
Main takeaway was:
During the glucose tolerance test, the men who had been eating carbohydrates for two days had remarkably stable blood sugar levels. But the other men’s blood sugar levels shot up to abnormally high levels. The men who had been eating lots of fat got results that suggested severe diabetes. Remember, these were healthy young men who had been eating practically nothing but fat for only two days.
From these results, Sweeney concluded that a high-carbohydrate diet helps to improve the body’s ability to tolerate carbohydrates. In contrast, high-protein diets, high-fat diets, and fasting undermine the body’s ability to control blood sugar. In a follow-up article , Sweeney suggested that some patients might have abnormal glucose tolerance test results because of the diet that their doctors had been urging them to follow, rather than because of some underlying medical problem.
Some of the sources to review