"Details of a large heart safety study presented on Monday appear to give Merck and Cos diabetes drug Januvia a clean bill of health possibly setting the stage for a return to sales growth for the drugmakers biggest product.  A view of the Merck  Co. campus in Linden New Jersey March  . REUTERSJeff Zelevansky  Merck in April said the study called Tecos of  patients with type  diabetes and a history of heart disease demonstrated that adding Januvia to usual care did not increase major heart problems any more than adding a placebo removing a cloud that has been holding back sales of the medicine and the companys share price.  Januvia an oral medication known chemically as sitagliptin that helps lower blood sugar levels had sales of about  billion in  plus another . billion for the related combination product Janumet  On the studys main focus after about three years . percent of Januvia patients had experienced cardiovascular death nonfatal heart attack nonfatal stroke or hospitalization for unstable angina versus . percent in the placebo group.  The detailed results also showed no increase in hospitalization for heart failure which had been a particular concern with DPP inhibitors the class to which Januvia belongs. There were  such hospitalizations for Januvia and  in the placebo group according to data also published in the New England Journal of Medicine.   We can be reassured we can use this drug for glucose lowering without affecting the already high cardiovascular risk in people with type  diabetes said Professor Rury Holman the studys lead investigator who presented the data at the American Diabetes Association meeting in Boston.  For the heart failure concern raised by other agents in the class there is no difference with placebo he added.  There was also no significant difference between Januvia and placebo in infections cancer kidney failure or severe hypoglycemia which is dangerously low blood sugar researchers reported.  Acute pancreatitis a concern with some diabetes drugs was uncommon but higher with Januvia  versus . That was not statistically significant.  Numerically this is hardly a major risk just something we need to keep an eye on Holman said.  Pancreatic cancers also uncommon were numerically fewer with Januvia  versus .  Death from any cause occurred in . percent of Januvia patients versus . percent for placebo.  The Tecos heart safety study was conducted by an independent academic research collaboration between the University of Oxford Diabetes Trials Unit and the Duke University Clinical Research Institute. It was undertaken after heart safety concerns were raised over other diabetes medicines."