CHICAGO--(BUSINESS WIRE)--New data from an investigational study released at the American Diabetes Association (ADA) 67th Annual Scientific Sessions showed that initial combination therapy with JANUVIA™ (sitagliptin) and metformin demonstrated significant improvement in markers of beta cell function in patients with type 2 diabetes. Pancreatic islet beta cell function determines the ability of the body to produce insulin, a hormone which plays a central role in the regulation of blood sugar levels. New data from a separate pharmacologic study reported today in an oral presentation revealed that, when used in combination in healthy adults, the different mechanisms of action of JANUVIA and metformin had a complementary effect on glucagon-like peptide-1 (GLP-1) levels, another hormone that is an important regulator of blood sugar levels. This aspect of the mechanism of action of metformin used in combination with JANUVIA was previously unknown. GLP-1 acts, in part, by enhancing pancreatic beta cell insulin production and secretion.