Do you mean type 2 diabetes? As far as I know, its to do with diet and lifestyle choices, which are usually of no fault of the childs. Im not sure there is a genetic factor, but I would imagine so as it is a common problem. Sorry I cant be of any more help.
Type 2 diabetes you mean? From the evidence so far, it is due primarily to lifestyle factors and genetics, i.e. eating too much unhealthy (saturated fat type foods), not doing enough exercise and complicated by genetics where people are predisposed to get the condition.
Im not an expert but the key factors to reduce your chances of getting the disease is to eat healthily and have an active lifestyle.
Obviously consult a medical doctor for further information.