Bristol had announced last month that it would no longer conduct research to discover new drugs for diabetes, hepatitis C and neurological conditions, but would increase spending on medicines that harness the immune system to fight cancer.
That refocus led to speculation that Bristol would seek to sell its share in the non-U.S. part of the diabetes joint venture to AstraZeneca.
Bristol spokeswoman Laura Hortas declined to comment on the reported deal. Officials at AstraZeneca did not immediately respond to requests for comment.
The joint venture includes the oral medicines Onglyza, Kombiglyze and Forxiga, as well as the injectable treatments Bydureon and Byetta.
Demand for many of these products has been relatively slow to build up and Forxiga, also known as dapagliflozin, was rejected by U.S. regulators in 2012.