A Pharmacy and Therapeutics (P&T) committee is the group that formally decides what goes on a formulary. Convened by a PBM, an insurer, or a large employer's benefits consultant, it is typically made up of physicians, pharmacists, and other clinical experts who review the evidence for each drug — efficacy, safety, and how it compares with alternatives — alongside cost data, then vote on whether to list it, at which tier, and with what restrictions such as prior authorization or step therapy.
For GLP-1 medications, the P&T committee is where decisions like "cover tirzepatide but not semaglutide" or "cover for diabetes but exclude for weight management" are made, often shaped by the rebates the PBM has negotiated. Formularies are usually revisited at least annually, which is why coverage can change from one plan year to the next. See how to determine if your formulary covers GLP-1 medications.