The causes of type 2 diabetes have much more to do with lifestyle issues, particularly obesity. But weight doesn’t tell the whole story. In fact, it’s unlikely that type 2 develops because of any one thing. Instead, a number of factors appear to come together, potentially even magnifying each other, with unhealthy results. Among the factors that may come into play:
Genetics. Patterns in twins indicate how strong the genetic link is — and it’s much stronger with type 2 than with type 1. In the case of type 2, if one identical twin has diabetes, the chances of the other getting it are as high as 75 percent. If one parent has type 2, there’s a 20 to 30 percent chance the kids will develop it, too. (If both parents have type 2, the risk to children is about the same as that shared by identical twins.) This makes type 2 a serious concern for ethnic groups that seem predisposed to it — and those groups are not the same ones that are most susceptible to type 1. Whites are most likely to get type 1, but type 2 is more prevalent amoung African Americans, Latinos, Native Americans, Pacific Islanders, and Asian Americans.
Inactivity. Physical activity improves the body’s use of insulin. This happens for a variety of reasons. Muscle, for example, uses glucose more efficiently than other types of tissue, and exercise builds muscle. Unfortunately, the opposite is also true: Lack of physical activity makes cells more prone to insulin resistance. It also contributes to weight gain.
Poor diet. How much you eat matters. But what you eat is also important. And the fat-laden foods so common in the American diet are more likely to pack on pounds than comparable amounts of other, leaner foods.
Age. Type 2 diabetes becomes more common with age, in part because cells in older bodies tend to be more insulin resistant. But it’s also true that people tend to become more sedentary with age. Their metabolism slows down, yet they eat just as much — or more. All of those elements are a prescription for an increased risk of diabetes.