Immigrants from a variety of places have a very low incidence of diabetes for up to 10 years. Those who live in the US longer, however, fare much worse. One of two things is going on here. The first could be that people arrive here relatively healthy, and then America is so bad for you that they develop diabetes in large numbers. The second is that they already have diabetes, but it’s undiagnosed, and our care of them is so bad that we’re not picking up on it for at least ten years.