But aggressive treatment can lower the risks.

“You really have to be on top of these kids and individualize therapy for each person,” said Dr. Barbara Linder, a senior adviser for childhood diabetes research at the National Institute of Diabetes and Digestive and Kidney Diseases, which sponsored the new study.

Sara Chernov, 21, a college senior from Great Neck, N.Y., learned that she had Type 2 diabetes when she was 16. Her grandfather had had both legs amputated as a result of the disease, and one of the first questions she asked was when she would lose her legs and her eyesight.

A doctor scolded her for being fat and told her she had to lose weight and could never eat sugar again. She left the office in tears and did not go back; soon after, she joined the study at Columbia. Like many of the children in the program, she did not even know how to swallow a pill.

Ms. Chernov believes that the disease “is not a death sentence,” she said, if she is careful about controlling her blood sugar. But it has been a struggle. Her family tends to be overweight, she sometimes craves sweets and she has orthopedic problems that have required surgery and have made it hard for her to exercise. She is also being treated for high blood pressure.

A few weeks ago, because her blood sugar shot up despite the diabetes pills she was taking, Ms. Chernov began using insulin.

Most of the participants in the study came from low-income families: 42 percent had yearly incomes under $25,000, and 34 percent below $50,000. About 40 percent were Hispanic, 33 percent black, 20 percent white, 6 percent American Indian and less than 2 percent Asian. Poor people and minority groups have some of the highest rates of obesity and diabetes in both adults and children.

Dr. Phil Zeitler, an author of the study and a professor of pediatrics at the University of Colorado, Denver, said many participants lived with a single parent or guardian and, like Ms. Chernov, came from families with a history of diabetes and had relatives with kidney failure or amputations.