Blenny has been on the sidelines of all four major races this year, with the result that he is not yet ready to start his next campaign.
He had been a full-time winner in 2015 but lost to a resurgent Ferrari in the final race.
“We are talking about my life and I don’t want to be in a position where I feel like my life is not in a good place,” Blenny said.
The Italian has been plagued by a hamstring injury since the start of 2016, which has prevented him from being able to race full-force in the past.
The 31-year-old has also suffered from illness and he missed the start to 2017 due to the World Cup and the European Championship.
Blenny, who has won three races in a row and scored a victory in a qualifying session on Sunday, is hoping to return to the track for a third time next year.
He has also been testing at the Australian Grand Prix in September.