OBJECTIVE: To estimate trends in total payment and patients' out-of-pocket (OOP) payments of noninsulin glucose-lowering drugs by class from 2005 to 2018. RESEARCH DESIGN AND METHODS: We analyzed data for 53 million prescriptions from adults aged >18 years with type 2 diabetes under fee-for-service plans from the 2005-2018 IBM MarketScan Commercial Databases. The total payment was measured as the amount that the pharmacy received, and the OOP payment was the sum of copay, coinsurance, and deductible paid by the beneficiaries. We applied a joinpoint regression to evaluate nonlinear trends in cost between 2005 and 2018. We further conducted a decomposition analysis to explore the drivers for total payment change. RESULTS: Total annual payments for older drug classes, including metformin, sulfonylurea, meglitinide, α-glucosidase inhibitors, and thiazolidinedione, have declined during 2005-2018, ranging from -$271 (-53.8%) (USD) for metformin to -$2,406 (-92.2%) for thiazolidinedione. OOP payments for these drug classes also reduced. In the same period, the total annual payments for the newer drug classes, including dipeptidyl peptidase-4 inhibitors, glucagon-like peptide 1 receptor agonists, and sodium-glucose cotransporter 2 inhibitors, have increased by $2,181 (88.4%), $3,721 (77.6%), and $1,374 (37.0%), respectively. OOP payment for these newer classes remained relatively unchanged. Our study findings indicate that switching toward the newer classes for noninsulin glucose-lowering drugs was the main driver that explained the total payment increase. CONCLUSIONS: Average annual payments and OOP payment for noninsulin glucose-lowering drugs have increased significantly from 2005 to 2018. The uptake of newer drug classes was the main driver.