Consultant cardiologist Dr Neil Grubb prepared a report based on medical information he was given about William Payne, 53.
He said that as Mr Payne had blacked out on four occasions, it was "reasonable" that he was not told to stop driving.
But after being told at the inquiry that Mr Payne told another doctor he had not suffered any blackouts when going through a medical test for his HGV licence he said that was "wrong".
Dr Grubb also said he would have ordered that a tilt table test was carried out on Mr Payne after the blackout episode he suffered in April 2008. The hearing was told it was carried out in December 2010, after the fatality.
Mr Payne, from Bishopbriggs, was driving his 4x4 on December 17, 2010, down North Hanover street in Glasgow city centre, when he collided with Mhairi Convy, 18, and Laura Stewart, 20.
He also injured Mark Hopwood, 39, who managed to survive.
Yesterday at Glasgow Sheriff Court Dr Grubb said he had medical records which he used to compile a report about Mr Payne.
Under cross-examination by Dorothy Bain QC, Dr Grubb said that he would have ordered a tilt table test as early as April 2008.
The tilt table test is used to diagnose fainting. When Mr Payne underwent the test after the incident his heart paused for 10 seconds.
Dr Grubb said that it was "entirely possible" that if the test was carried out in April 2008 that it would have had the same result.
The inquiry before sheriff Andrew Normand continues.