The 27-year-old Australian was engaged in a tight battle with Novak Djokovic when he suffered the injury and retired while trailing 7-6(3) 0-1 in the second set, handing the Serbian great a seventh title in the Chinese capital.
"I was feeling quite good, then I felt something midway through the end of the first set. Yeah, it gradually got a little worse," De Minaur told reporters.
"Felt something in the adductor. I don't know what it is yet. I've got to get some more scans. My plan is to go to Shanghai and get scans."
In 2024, De Minaur was forced to withdraw from a Wimbledon quarter-final against Djokovic because of a hip injury and missed the singles tournament at the Paris Olympics before returning at the US Open some seven weeks later.
De Minaur was scheduled to play next this season at the Shanghai Masters, where he reached the quarter-finals last year and which kicks off on Wednesday.
If he is able to play, the Australian number one still has a chance of making the eight-strong field for the ATP Finals, especially after a slot opened up when Jannik Sinner announced on Tuesday he would play no more tennis this year.
De Minaur, who reached the semi-finals of the season-ending ATP Finals in Turin last year, said he had been pleased with his form in Beijing.
"Everything except for the end was really positive," he added.
"There was a lot of good tennis. I played some great stuff. Felt amazing on the court."