A: Type I and type II diabetes both seem to have a genetic component, but in neither form is there any absolute way of determining whether or not you are going to get it, because a whole host of other factors come into play, including (as discussed earlier) your lifestyle choices—diet and exercise—as well as possible environmental triggers that still need to be identified with certainty. There is definitely a link between genetics and type I diabetes, but the actual identity of the problem gene is not known. And the link is relatively weak compared to type II. By some estimates, if both your parents have type I diabetes, the chances are somewhere between 1 in 10 and 1 in 4 that you will develop it, whereas if both your parents have type II diabetes, you have a 1 in 2 risk. If your identical twin develops type I diabetes, you have about a 50 percent chance of developing it, too, whereas if your identical twin develops type II, you have about a 75 percent risk. With type II diabetes there is also a racial component to the genetics of diabetes, for certain ethnic groups, among them those of African descent, are prone to this form of diabetes—perhaps in our case because of that thrifty gene we discussed earlier. But genetically caused diabetes is almost certainly more the exception than the rule, and most of the people who are involved in the current epidemic of type II diabetes that is sweeping this country should probably put the blame on their diet and exercise choices rather than on their parents or grandparents. 

         It has been shown that people who in areas that have not become westernized in their diet habits (eating too much fat, too few whole grains, and too little fiber) and their exercise habits (living a sedentary lifestyle) do not get type II diabetes, no matter how high their genetic risk. The major associated risk factor for diabetes is obesity, particularly the type where you carry the most of your fat around your waist. And even if you have both racial and genetic tendencies toward diabetes, studies indicate that modesty weight loss, about 5 to 7 percent of body weight, and regular exercise can at least delay, if not altogether prevent, the onset of diabetes. So if one or both of your parents has type II diabetes, you and your siblings should be especially vigilant about diet and exercise in order to offset the increased risk for developing the disease. Discuss appropriate screening, lifestyle interventions, and treatment with your physician.