Dr. Mark Atkinson, professor of pathology and pediatrics at the University of Florida who was the study leader, and Dr. Peter Butler, director of the Larry L. Hillblom Islet Research Center at the University of California, Los Angeles, found cell mass was increased about 40 percent in the pancreas of deceased organ donors who had type 2 diabetes treated by incretin therapy.
Incretin therapy takes advantage of the action of the gut hormone glucagon like peptide 1 (GLP-1) to lower blood sugar in people with type 2 diabetes, the researchers said.
Although there have been conflicting reports on the effects of the incretin class of drugs on the pancreas in animal studies, this is the first report to note such changes using human pancreas, the study said.
"There is an increasing appreciation that animal studies do not always predict findings in humans," Butler said in a statement.
The study, published in the journal Diabetes, found the pancreas of the individuals who had been on incretin therapy were larger than the organs from those who had been on other types of diabetes therapies, and was associated with increased cellular proliferation.
Pancreas from incretin treated individuals also had an increase of pancreas dysplasia, an abnormal form of cell proliferation that is a risk factor for pancreatic cancer, the study said.
Of the eight donors who were on incretin therapy, seven had been taking sitagliptin, or Januvia, marketed by Merck and one had been on exenatide, or Byetta, sold by Bristol-Myers Squibb, the study said.
These and other similar drugs are currently under investigation by the U.S. Food and Drug Administration for their possible links to pancreatitis and pancreatic cancer, the researchers said.