One of the best diabetes clinics in the entire world has basically "cured" even very advanced cases with just diet. The cure? You eat virtually no carbohydrates. This isn't some quack either but a respected doctor and scientist. Do you know the amount of carbs needed per day? Zero. The human body can manufacture everything it needs to run out of fats and proteins (obviously salt, vitamins and minerals are required as well).

In some kind of protracted crises where insulin isn't available diet is going to be the only option. But since most diabetes is cased by eating the SAD not having that "diet" may save your life anyways.