Ask your friend what she wants you to do. Seizure requires medical intervention. But better t to detect low blood sugar before it causes seizure while she is conscious and can take oral sugar to correct the situation. Frequent testing of blood sugar particularly if she is feeling 'off' will be very important.
Try and help her to the ground, move anything nearby so she doesn't hit it, and call an ambulance. Don't try to hold her still or put anything in her mouth while she's seizing, it could hurt her or you. Just wait for it to pass.