I am purchasing my grandmother's diapers and I thought her insurance would pay for it. Who can I talk to?

To the best of my knowledge Insurance does not cover diapers. I paid for my mothers for three years, and it was never covered under Medicare, or her secondary. If you want to see if it is covered, you would contact her insurance provider and has what her coverage is. If she is on Medicaid, I would contact her local Area on Aging to review what resources they have for your area.
Blessings
Bridget Wetterer