Varela joined Man United in 2013 but he initially struggled for first team opportunities at Old Trafford.
Genoa were said to be interested in the defender but van Gaal has used Varela much more often in recent weeks amid an injury crisis at the club.
“He gave me the opportunity and luckily I’ve played for many matches in a row.”
Varela’s inclusion in the team was brought on by injury but the right-back has stayed in the team on merit by putting in a number of top performances.
The 22-year-old is one of a number of young players to impress in the first team as of late, with Timothy Fosu-Mensah, Cameron Borthwick-Jackson and Marcus Rashford also making the step up. Varela has displayed a first class attitude recently and he is quickly endearing himself to United fans.