By Lisa Ellis
InteliHealth Staff Writer
NEW ORLEANS — The second part of a major study aimed at finding a way to prevent type 1 diabetes has produced disappointing results, researchers announced.
No more than 10 percent of people with diabetes have type 1. It stems from an immune reaction that causes the body to destroy some of its own cells — in this case, the beta cells in the pancreas that make insulin.
The medical community understands pretty well how to prevent type 2, the much more common type of diabetes. Maintaining a normal weight and getting regular exercise often can head off the disease, although family history also makes a difference.
Type 1 can be prevented, too — but so far not in humans. Researchers have discovered 120 different ways to protect laboratory mice from the disease, said Jay Skyler, M.D., a principal researcher on the type 1 prevention study.
Relatives of people with type 1 diabetes have 10 to 20 times the average risk of developing type 1 themselves.
Investigators in the study, called the Diabetes Prevention Trial-Type 1 (DPT-1), identified and tested more than 100,000 relatives of people with type 1, in an attempt to find a way to protect them. Several hundred agreed to participate in the study.
Researchers reported their first results at the American Diabetes Association (ADA) Scientific Sessions in 2001. In this part of the study, relatives who faced the highest risk took insulin injections in an attempt to head off diabetes.
The treatment did not work. People who took the injections developed diabetes at virtually the same rate as a control group who did not.
At the ADA's current meeting, Dr. Skyler presented the outcome of a related study that tried to prevent diabetes in 372 relatives with somewhat lower risk.
Researchers did not want them to have to get insulin injections, said Dr. Skyler, director of endocrinology, diabetes and metabolism at the University of Miami. So instead they received insulin pills.
Insulin given as a pill does not lower blood sugar. Insulin, a protein, is digested by the stomach and never reaches the bloodstream. But reducing sugar was not the aim in this case, Dr. Skyler said.
Instead, researchers hoped to trigger reactions in the immune system that might stop the destruction of the beta cells in the pancreas.
It didn't work, Dr. Skyler said. People who took the insulin pills developed diabetes at the same rate — 35 percent within five years — as those who received a placebo, or fake pill.
This is the third large study that attempted to prevent type 1 diabetes, said Joseph I. Wolfsdorf, M.D., director of the Diabetes Program at Children's Hospital Boston.
Because many participants were children, investigators may have erred on the side of safety by giving too small a dose of injected insulin, said Dr. Wolfsdorf, a DPT-1 investigator and associate professor of pediatrics at Harvard Medical School.
The DPT-1 study is not completely over, however. Investigators are enrolling new possible participants, and they plan to begin testing other agents that potentially may prevent type 1 diabetes.