Dallas ? A Dallas-based researcher says he’s pulled off a medical first: successfully treating mice and rats dying of insulin-dependent diabetes without using insulin.

Dr. Roger Unger, chairman of diabetes research at University of Texas Southwestern Medical School, is quick to warn that practical applications, if any, are years away. But the research team he headed used high levels of leptin, a substance naturally produced by fat cells, to somehow reverse the otherwise fatal effects of diabetes.

If the experiment is repeated in other labs, and then if leptin can be adapted to treat humans, it might offer the first alternate to the multiple insulin injections used by millions of people who have Type 1 diabetes, Unger said.

How surprising was the result of the experiment?

“It would be like finding aliens landing in your backyard,” Unger said.

It’s not easy for diabetes to surprise Unger. He’s been a top researcher for decades with a long list of honors from many major diabetes-related organizations. At 84, he’s still someone that others in the field pay attention to.

His latest findings were published Monday in the Proceedings of the National Academy of Sciences.

Leptin may blunt the short-term impact of Type 1 diabetes: the rapid weight loss and altered blood chemistry that make the untreated disease fatal. It may also help control the longer-term effects of the disease.