In the first major national analysis of diabetes trends among American youth, researchers Saturday reported an alarming 23 percent rise in type 1 diabetes incidence over an eight-year period ending in 2009.

The surprising increase, being reported at a meeting of the American Diabetes Association, comes amid similar growth of type 2 diabetes in children. But unlike type 2, which is linked to the high prevalence of obesity in youth, researchers have no explanation for why the autoimmune form of the disease is growing at such a clip.

Funded by the Centers for Disease Control and Prevention and the National Institutes for Health, the study used data from 20,000 children and youth under 20 at multiple hospitals and health centers in five states. The researchers found that the incidence of type 2 diabetes over that period increased 21 percent.

The study found that children and adolescents with diabetes have measurable signs of complications including nerve damage that could lead to amputations. It also identified early signs of cardiovascular damage raising risks for future heart disease.

CDC estimates that there are 18.8 million Americans who have been diagnosed with both types of diabetes and another seven million undiagnosed, costing $116 billion in direct medical costs. Of those, between five percent and 10 percent are thought to have type 1 diabetes.

Another study released Saturday found most people with type 1 do not meet treatment targets and they are likely to be overweight or obese as adults. Failure to reach treatment targets raises the risk for complications.

Type 1 diabetes, formerly known as juvenile diabetes, is an autoimmune disorder where the body loses the ability to produce insulin, the hormone that controls the level of sugar in the blood. Type 1 diabetics are insulin dependent while type 2 diabetics in many cases can manage the disease with changes to diet and exercise.

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