Americans and Europeans eat too much fat and too little carbohydrate and fiber, and they get too little exercise. Type 2 diabetes is common in people with these habits. The ethnic groups in the United States with the highest risk are blacks, Mexican Americans, and Pima Indians. In contrast, people who live in areas that have not become Westernized tend not to get type 2 diabetes, no matter how high their genetic risk. Obesity is a strong risk factor for type 2 diabetes.
Obesity is most risky for young people and for people who have been obese for a long time.
Gestational diabetes is more of a puzzle. Women who get diabetes while they are pregnant are more likely to have a family history of diabetes, especially on their mothers' side. But as in other forms of diabetes, nongenetic factors play a role. Older mothers and overweight women are more likely to get gestational diabetes. Your child's risk is doubled if you developed diabetes before age 11.