Shanmugadas (74) is survived by wife and two daughters.
He was the Health Minister in the E K Nayanar Ministry in 1996.
Shanmugadas, who represented Balusseri constituency in the Kerala Assembly seven times from 1967, had served as minister three times.
Among those who condoled his death included Defence Minister A K Antony and CPI(M) leader Kodiyeri Balakrishnan.
Condoling the death, NCP chief Sharad Pawar said, Shanmugadas "represented a different class of public leaders who had devoted his life for selfless service to the people."