I doubt if it's caused by iabetes, but it could be more serious
Having said that, I've been prone to ingrowing toenails all my adult life [diabetic only 10 years] I have what are called Morton's Feet, where the first metatarsal on each foot is short. this makes the second toe project in front of the big toe.
It can make ingrowing more likely.
I used to go to the doc and end up on antibiotics. As soon as I finished the course, the problem came back. then I went to the podiatrist, who clipped down the side of the nail and lifed out he troublesome bit with forceps. Treated the toe with iodine and a dressing and I'd be OK for months.
I noted how she did the clipping, so I got myelf the right kind of clippers and whenever I feel the problem starting, I clip and remove the spur bit. I've kept my toes healthy several years now. If I do get a problem I can't deal with myself, I'll go back to the podiatrists.
I also wear socks with separate toes, which also helps.
Hana