April 7 (Reuters) - Merck & Co Inc said the U.S. Food and Drug Administration (FDA) declined an application to include information on the labels of its diabetes drugs - Januvia and Janumet - that the treatments do not raise the risk of major heart problems.
Merck is reviewing the regulator's response to its application, the company said on Friday.
Some 29 million Americans have diabetes, but even when glucose levels are under control, the disease greatly increases the risk of heart disease and stroke, according to the American Heart Association.
Any evidence of heart-protective qualities carried by diabetes drug labels would therefore serve to boost sales of the drug.
The FDA in December allowed Eli Lilly and Co and German partner Boehringer Ingelheim to state on labels that their diabetes drug, Jardiance, reduces the risk of death from heart problems, potentially improving the drug's future sales.
The decision marked the first time a diabetes treatment was allowed by the agency to carry a label that said the drug cut the risk of cardiovascular death.
Jardiance, which belongs to a class of treatments called SGLT2 inhibitors, raked in nearly $202 million in 2016 sales.
With the updated label, some analysts have predicted Jardiance will bring $4 billion in sales by 2025.
Merck's Januvia and Janumet generated sales of more than $6 billion last year.
Januvia is an oral medication, known chemically as sitagliptin, that helps lower blood sugar levels. Janumet is a related combination product.
Merck had submitted its application to include heart safety data on the drugs' labels based on a keenly watched study involving 14,724 patients who had type 2 diabetes and a history of heart disease.
The study's results, announced in 2015, showed that adding Januvia to standard care did not increase major heart problems. (reut.rs/2nkYtt2)
Study data also showed no increase in hospitalization rates for heart failure, which had been a particular concern with DPP-4 inhibitors, the class of drugs to which Januvia belongs.
The study, which was undertaken after heart safety concerns were raised over other diabetes medicines, was conducted by an independent academic research tie-up between the University of Oxford and Duke University.
Type 2 diabetes, closely linked to obesity, accounts for more than 90 percent all diabetes cases. (Reporting by Natalie Grover in Bengaluru; Editing by Sai Sachin Ravikumar)