That's not exactly how it works. There are two types of diabetes, Type I and Type II. Type I you are born with. It is an autoimmune disorder where your body attacks your own islets of langerhans in the pancreas and destroys those cells. Without these, your body cannot produce insulin, thusly the OP's son's pump. These people have diabetes through no fault of their own.
Type II can be prevented, although there is a strong genetic factor. Type II diabetics traditionally eat a lot of crappy food, don't get much exercise, and are almost always overweight. Type II is just a case of insulin sensitivity. Type II diabetics have had such high levels of glucose in their blood, that it takes more and more insulin for their cells to take any glucose in. Their body cannot keep up with the insulin production and people "become" type II diabetics. This can often be controlled with diet and exercise combined with weight loss. This requires effort, though, so many type II diabetics rely on medications.
