The former Congress leader was admitted in Gauhati Medical College and Hospital (GMCH) where he was undergoing treatment.
In the Assam cabinet, he had held the portfolios of supplies and irrigation as a minister.
Dey had completed his MBBS degree from University of Calcutta. He was elected as MLA for the first time in Assam Legislative Assembly election from Hojai constituency in 1991.
He had served as an MLA between 1991 and 2006 as a Congress member. Later, in April 2021 he joined Bharatiya Janata Party (BJP).
In 2011, he was again elected to the state legislative assembly.