Re: ingrown Toenail. If you are diabetic, make and appointment to see a healthcare professional immediately. Be alert for signs of infection including redness swelling and drainage (fluid or pus). A portion or the entire nail may need to be removed by the doctor (under local anesthesia in a clean/aseptic environment of course). Good luck.
Have it evaluated. See a podiatrist and have it evaluated and managed to avoid possible complications.
Antibiotic ointment. Put some neosporin or similar antibiotic ointment down the tender edge several times daily. It will soften it and help ease the discomfort. Don't try to cut it out yourself. You'll likely leave a sharp edge and the toe will get infected. See a podiatrist. They will fix it quickly and professionally.