Liz Szabo

USA TODAY

The prevalence of diabetes in children shot up dramatically between 2000 and 2009, a new study shows.

The amount of type 1 diabetes, an autoimmune disease, climbed 21% from 2000 to 2009, to 1.93 per 1,000 children. The prevalence of type 2 diabetes — which is associated with obesity — jumped more than 30% in the same period, to a rate of 0.46 per 1,000 kids, according to a study presented Saturday at the Pediatric Academic Societies' meeting in Vancouver, Canada.

Nationwide, nearly 167,000 children and teens younger than 20 have type 1 diabetes, while more than 20,000 have type 2, says study author Dana Dabelea, of the Colorado School of Public Health in Aurora, Colo.

"These increases are serious," Dabelea says. "Every new case means a lifetime burden of difficult and costly treatment and higher risk of early, serious complications."

The new study, published in the Journal of the American Medical Association, is the most comprehensive available, said David Ludwig, director of the New Balance Foundation Obesity Prevention Center at Boston Children's Hospital, who was not involved in the study. The research, called the SEARCH for Diabetes in Youth Study, included 3 million children and adolescents in different regions of the USA.

Researchers acknowledge that the study doesn't include information from the last five years.

"We don't know what happened in the last five years," Ludwig says. "Most likely, things have gotten worse."

Type 1 diabetes, once known as juvenile diabetes or insulin-dependent diabetes, occurs when the pancreas makes little or no insulin, a hormone that the body needs to let sugar to enter cells and produce energy.

In type 2 diabetes, once known as "adult-onset" diabetes, the body becomes resistant to the effects of insulin or doesn't make enough insulin, according to the Mayo Clinic.

Doctors have made major progress in treating type 1 diabetes and preventing complications, Ludwig says. But children who develop type 2 diabetes face serious risks, which are compounded by the fact that most are already obese. Together, obesity and diabetes increase their lifetime risk of heart attacks, strokes, kidney failure, blindness and amputations.

Diabetes affects 25.8 million people of all ages in the USA, or about 8.3% of the population, according to the National Institute of Diabetes and Digestive and Kidney Diseases, part of the National Institutes of Health.

In the past, type 2 diabetes was considered a disease of middle or old age, developing in overweight or obese adults, Ludwig says. The fact that kids are developing this disease so young shows the seriousness of the country's obesity crisis, he says.

The increase in type 2 diabetes appears to be driven by increasing rates of obesity, lack of exercise and low-quality diets, Ludwig says. Scientists are less sure about the reasons for increasing rates of type 1 diabetes. But some evidence suggests that it may be related to changes in the microbiome — the collection of bacteria and other microbes that live in and on the body, especially in the digestive tract, Ludwig says.

In a new book, Missing Microbes, Martin Blaser of the NYU Langone Medical Center notes that the human microbiome is changing, due to lifestyle changes and medical practices, such as the increasing use of antibiotics.

Eating diets rich in vegetables and plant fiber encourages the growth of gut bacteria that help to break down these foods, Ludwig says. As people eat a more processed diet, with little plant fiber, these bacteria may decrease. Although doctors aren't totally sure how these bacterial changes affect the body, scientists are examining whether the trend could be related to rising rates of certain chronic diseases, from asthma and allergies to autism.

"Gut bacteria influence inflammation and the immune system," Ludwig says. "As our diet changes and is increasingly sterile, we're getting rid of a lot of beneficial bacteria."