Deductions & credits

If per diem benefits that do not exceed the allowed daily amount are not supposed to be taxable, doesn't reducing your medical expense by those same benefits received make them taxable by virtue of reducing your medical expense deduction?  Everything I've found says you must reduce your medical expenses by any REIMBURSEMENT received.  Per diem benefits are not reimbursement (look up the definitions in the dictionary), they are paid to the policyholder REGARDLESS of expenses incurred.  I've spent hours trying to find something definitive on this with no success.  Per diem benefits are daily benefits you receive for being chronically ill or otherwise qualifying to receive the benefits.  Reimbursement benefits are benefits received for having spent money on something.  There's a difference.