If it is Type II, then you just need to stay in a healthy weight range. If it is Type I, there is not much you can do - you either have the gene or you don't. In general, it is a good idea to eat a fairly low-carb diet. Avoid eating a lot of wheat, potato, rice, and sugar. You are actually better off eating sugar than white rice in terms of how it raises your blood sugar levels. Oh, and avoid juice of any kind. You can encourage your father to eat this way too. Since I have a family member with Diabetes, we all cut back on the carbs and are healthier as a result. You can't go wrong with lots of veggies, fruit, olive oil, dairy, and proteins.

The American Diabetes Association website is a great place to start with diabetic meal planning. Anthing that raises blood sugar should be avoided and the site can educate you about foods that do so. Here's the link: http://www.diabetes.org/food-and-fitness/

Is he Type I or Type II? (By the way, this is more of a cooking and kitchen emergency Q & A, more cooks than Doctors here.)