Sabine Kehm said the seven-time F1 world champion has always been a very private person so the decision to leave his fans in the dark has been in his best interest.
Ms Kehm told German media: “Michael has consistently drawn a clear line between the public and the private, which has always been accepted by the fans and the media.
“The decision to protect his privacy from the public has been met in Michael's interest."
Little is known about Michael Schumacher's condition
The decision to protect his privacy from the public has been met in Michael's interest
Michael Schumacher was skiing in the French Alps above Meribel in December 2013 with his 14-year-old son Mick when he fell and hit his head on a rock.
Despite wearing a helmet, the record-breaking driver suffered traumatic brain injury and was put into a medically induced coma.
In April 2014 Schumacher, who drove for Benetton, Jordan, Mercedes and Ferrari, was withdrawn from the coma and moved to a rehabilitation ward in Lausanne, Switzerland before being brought home to Germany in September 2014.
Michael Schumacher in pictures Fri, May 26, 2017
Seven time F1 World Champion, Michael Schumacher is one of the greatest to have driven a racing car.
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Michael Schumacher at the Belgium Grand Prix in 1991
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Few details have been released about his condition, with Ms Kehm only revealing in May 2015 his condition was slowly improving.
A year later his lawyer told a German court Schumacher, who still holds the record for most championships wins, “cannot walk”.
Ms Kehm revealed the day of his accident is always on her mind.
She said: “I was with my parents, we had just celebrated Christmas.
“Then a French journalist called me, Michael Schumacher had an accident, he was asking for confirmation.
“In the afternoon I found out that the situation was serious. The next morning I was at the hospital in Grenoble.
"A journalist had dressed up as a priest, and another stated to be Michael's father.
“In the beginning, the hospital staff did not know who was who. It was a difficult time?"
Schumacher is a seven-time world champion
Her comments come as the F1 world prepares for one of the most iconic races on its calendar – the Monaco Grand Prix – which German driver Schumacher won five times.
The former Ferrari and Mercedes driver is the joint second most successful driver in Monaco ever – his five wins in the principality is tied with Graham Hill.
Brazilian F1 legend Ayrton Senna is the most successful driver ever in Monaco – with six wins at the iconic race track.
Manager Sabine Kehm said Schumacher is a private person
Jenson Button is set for a brief comeback at the Monaco Grand Prix
The current F1 season sees Schumacher's former teams – Ferrari and Mercedes – vying for both the drivers and constructors titles, with Ferrari's Sebastian Vettel leading the title race ahead of Lewis Hamilton.
The race also sees the return of fellow long-time F1 driver Jenson Button, who is preparing to make his comeback at the Monaco Grand Prix this weekend after retiring last season.
The former world champion will drive Fernando Alonso’s McLaren as the Spaniard competes in the Indy 500.
Button, who won Monaco eight years ago, managed to overtake fellow Briton Lewis Hamilton in practice on Thursday but ended 12th.
Ferrari’s Vettel ended first in the second practice round while Hamilton ended the session eigth.
Hamilton was quickest in the first session and will be hoping for a win on Sunday in a bid to oust Vettel from the top spot in the championship standings.