Currently coding insulin infusion for Mississippi clinic. We are using 96521, 96365 (with 59 modifier, sometimes also 96566) with J1817 for the insulin infused. J1817 is for 50 units of insulin which is equal to 0.5mL. We are using JZ modifier for no discard based on provider documentation. Some payers are denying as missing/inappropriate modifier. We have researched CMS and payer guidelines and are still coming to the conclusion that we are coding appropriately but continue to get denials. Can someone please help or advise?