Boston Children’s Hospital Finds Root Cause of Diabetes

This seems to be the peer-reviewed journal article: http://diabetes.diabetesjournals.org/content/62/5/1665.abstr...

From reading the abstract, it seems that inhibiting the mentioned pathway prevents islet cell transplant rejection. Arguing that the same mechanism is "the root cause of type I diabetes" sound like sensationalist speculation.

Does discovering the mechanism through which diabetes is caused in animals directly correlate to the process that causes diabetes in humans? I would assume it is a good indicator given the number of studies that use animals, but can they really claim they have definitely identified the root cause?