The scientific journal Nature published a retraction of a study from 2000 in which researchers from Calgary and Korea said they reversed Type 1 diabetes in mice.

Lead author Hyun Chul Lee of Yonsei University in Seoul, South Korea, and two other authors sought the retraction in Thursday's issue, saying they could not reproduce the results of the gene therapy experiment.

Fellow study author Ji-Won Yoon of the University of Calgary is deceased. The final author, Su-Jin Kim, maintains the results are still valid and did not sign the retraction, the journal said.

In Type 1 diabetics, the pancreas produces little or no insulin, and patients need to inject it to keep their blood sugar levels stable.

In 2000, the researchers said the rodents' blood sugar levels were normal within two weeks of the treatment and stayed that way for five months.

It wasn't known if the approach would work in humans, and previous attempts to insert genes to regulate blood sugar levels eventually failed.