David Ludwig, MD, PhD, an endocrinologist at Boston Children’s Hospital, has written popular books espousing a low-glycemic, low-carbohydrate diet for weight control. He has argued that high-glycemic diets are contributing to the epidemic of type 2 diabetes.  But he hadn’t given much thought to carbohydrate restriction for type 1 diabetes until 2016.

At a conference, Ludwig met a surgeon with type 1 diabetes who maintains normal hemoglobin A1c levels (indicating high blood sugar control) on a very-low-carbohydrate diet. This surprised and impressed him: he had never seen any patient with type 1 diabetes able to completely normalize their hemoglobin A1cs. Moreover, most diabetes experts discourage very-low-carb diets, believing they pose a risk for hypoglycemia, or a dangerous drop in blood sugar. …