"The Prime Minister is ignorant and disrespectful of history, less literate in economics," Mr Sharma said in a series of tweets.
"The economy stands derailed, jobs lost and businesses shut," he said, blaming Modi for the slowdown.
"India had to suffer when an arth-shastri (economist) Prime Minister (Manmohan Singh) was replaced by a prachar-shastri (publicist) Prime Minister (Narendra Modi)," Mr Sharma tweeted.
"It is sad that India has a Prime Minister who is boastful, arrogant and in perpetual conflict with history, facts and ground realities.
"He has habitually insulted and misrepresented history, distorted facts and manufactured numbers," the former Union Minister said.
The Congress and BJP have been sparing no efforts to attack each other, mostly on social networking sites, ahead of the Gujarat election.
The latest opinion poll on Tuesday predicted that it is going to be a neck-and-neck contest between the two parties in the state where the BJP has been in power for the last 22 years.