The nutritional management of diabetes is complicated, and is discussed in detail in my textbook, Nutritional Medicine (www.doctorgaby.com).
People with type 1 diabetes do not make insulin in their body, and will therefore need to continue insulin therapy indefinitely. In many cases, people with type 2 diabetes can be managed effectively with dietary modifications and nutritional supplements. Dietary modifications that may be beneficial include losing weight if overweight; avoiding refined sugar and other refined carbohydrates; and emphasizing foods that are high in fiber (particularly legumes). Nutritional supplements that may lower blood sugar levels include chromium and biotin.
For diabetics with advanced kidney disease, dietary changes can be dangerous. In addition, starting a diet-and-supplement program may require a change in the dosage of diabetes medication. For these and other reasons, people with diabetes should always consult a knowledgeable healthcare practitioner before starting a nutrition program for diabetes.