Weight gain, poor nutrition, and lack of exercise reduce the action of insulin--a hormone that allows sugar to enter cells where it can be used for energy--a condition called insulin resistance. Initially, the body compensates for the resistance by increasing production. However, over time the ability of the pancreas to increase production doesn't keep up and blood sugar begins to rise, leading eventually to type 2 diabetes.
Orit Pinhas-Hamiel, M.D. of Sheba Medical Center in Israel and Philip Zeitler, M.D., Ph.D. of the University of Colorado reviewed articles and reports on type 2 diabetes in children and adolescents between 1978 and 2004. Although the review is limited to published data only, they found that type 2 diabetes accounts for up to 45% of new cases among adolescents. The authors cite higher percentages in areas such as New York, Taiwan, New Zealand, and Canada.
The rising percentages among certain ethnic groups are particularly striking. For example, 80% of new cases of pediatric diabetes in Japan and 70% of new cases among Native Americans are classified as type 2 diabetes. The Pima Indians in Central Arizona have the world's highest recorded rate of type 2 diabetes in adults, in addition to high rates of obesity. The authors observe that there is a close tie between the rate of type 2 diabetes among adults in a specific population and the appearance of it in children and adolescents.