The adult form of diabetes once only seen in people over the age of 40 is now being diagnosed in teenagers. For the first time, researchers have looked at the risk for young people of developing adult onset diabetes, an illness that can lead to devastating complications.

Doctors such as the University of Miami's Ronald Goldberg are troubled by what they are starting to see in their patients.

"We know that overweight and obesity have been increasing in the country generally, but importantly here for young people and children. And we know from the adult evidence that when the adult population puts on weight and becomes less active, the frequency of a number of number of diseases increases. And one of the earliest diseases to increase in its prevalence is diabetes and glucose intolerance," Dr. Goldberg says.

Glucose intolerance is a sign that the body is not using glucose or sugar properly, and may be on its way to developing diabetes. Before the latest study published in the New England Journal of Medicine, there was no hard data on what percentage of children and adolescents suffered from glucose intolerance.

Researchers at Yale University in Connecticut set out to do just that. They recruited 55 very obese children and adolescents of different ethnic backgrounds. The investigators checked to see how well the young peoples' bodies processed sugary drinks.

The study found that 25 percent of obese children and 21 teens had impaired glucose tolerance. Four adolescents in the study were found to have "silent" diabetes, meaning they were diabetic and did not know it.

Dr. Sonia Caprio led the research, published in the New England Journal of Medicine.

"What I want to make clear is certainly if the rates of obesity are going so high, and the severity of obesity is increasing, we are going to face up a number children coming down with Type Two diabetes in their second decade of life. It is worrisome because the longer the duration of diabetes, the longer you are at higher risk for complications," Dr. Caprio says. The complications of diabetes for someone who's lived with a poorly treated case of diabetes include blindness, kidney failure, heart disease and eventually death.

Around the world, an estimated 22 million children under the age of five are overweight, a risk factor for diabetes. At the University of Miami, Ronald Goldberg is a specialist in adult onset diabetes, but he's quickly becoming an expert in the corresponding children's disease.

"What we see in the rest of the world is populations in different stages along the path. In other words, the developing countries that have raised their standard of living to approximate more to what a western lifestyle is and are starting to become more overweight we are seeing diabetes emerge in adults where it wasn't present before. So, they're a step behind us. The next step is the kids," Dr. Goldberg says.

Experts agree that catching glucose intolerance early especially in children is important, because with diet the condition is reversible.