Study links childhood obesity, 'adult' diabetes

About one in four obese children are glucose-intolerant and at risk for developing a form of diabetes normally seen in adults, according to a new study.

"Most of these children are at high risk for type 2 (non-insulin-dependent) diabetes," said Dr. Sonia Caprio, a Yale School of Medicine endocrinologist who's the senior author of the report, published Thursday in The New England Journal of Medicine.

"If they develop diabetes before the age of 20, they face a lifetime of being at very high risk for complications from diabetes," she added.

Once seen only in adults, type 2 diabetes has been rising steadily in children, especially in adolescents who are black, Hispanic and Native American, according to reports from clinics around the country. Government surveys show the incidence of obesity among adolescents has tripled in the past 20 years, to about 14 percent of 12-19-year-olds.

The longer a person has diabetes, the greater the chances for developing disabling, life-threatening complications, said Dr. Francine Kaufman, president-elect of the American Diabetes Association. "We are seeing young people in their late teens who are already developing complications of type 2 diabetes," said Kaufman, director of the diabetes center at the Children's Hospital of Los Angeles.

Possible long-term complications from diabetes include early artery disease, often affecting legs and feet and leading to foot ulcers, early heart disease, kidney disorders, eye disorders and blindness and nerve problems.

The traditional juvenile, or type 1, diabetes (insulin dependent) most often appears in childhood or adolescence, and is more likely to be marked by normal body weight or even thinness.

Caprio and colleagues conducted their study to see if obese children have impaired glucose tolerance, which in adults is known to be a risk factor for type 2 diabetes.

The researchers tested glucose tolerance in 55 obese children aged 4 to 10, and 112 obese adolescents from 11 to 18 years of age. In all, 25 percent of the children and 21 percent of the adolescents had impaired glucose tolerance.

Four of the children had silent type 2 diabetes, which means they're not aware they're diabetic, and three moved from glucose intolerance to diabetes during the four-year study.

The children with impaired glucose tolerance frequently were insulin-resistant, a condition in which fat, muscles and liver cells are unable to use insulin. Eventually, the insulin-producing cells of the pancreas can't keep up with the body's demand for insulin, glucose builds up in the blood and type 2 diabetes begins.

Glucose intolerance in the study group was as prevalent among whites as among minority children, even though the latter group traditionally has had higher rates of diabetes. The condition was also more common among girls than boys.