Post-implementation changes in the procurement volume and patterns of oral hypoglycemic drugs under China’s National Centralized Drug Procurement policy: an interrupted time-series analysis in Shanghai

Diabetes is a major public health issue faced by countries worldwide. China has the largest number of diabetes patients globally, accounting for nearly one-quarter of the global diabetes population. Oral hypoglycemic drugs remain a primary treatment strategy for diabetes worldwide due to their convenience, cost-effectiveness, and non-invasive nature. To reduce drug prices and improve access, the Chinese government has implemented the National Centralized Drug Procurement (NCDP) as a regular, batch-based program. As of October 2025, 22 oral hypoglycemic drugs have been included. This study aimed to examine post-implementation changes in the procurement volume and patterns of oral hypoglycemic drugs following the NCDP policy in Shanghai. We conducted an exploratory analysis to characterize temporal trends in the procurement volume and procurement patterns of oral hypoglycemic drugs in Shanghai from 2016 to 2023. Interrupted time series (ITS) analyses were used to describe changes in procurement volumes and patterns among 16 policy-covered drugs and their potential clinical alternatives. Cross-correlation analyses (CCA) were applied to examine temporal associations between novel oral hypoglycemic drugs and traditional agents. The main outcome indicators included monthly procurement volumes, measured in defined daily doses (DDDs), Cohen’s d value, level and trend estimates derived from ITS analyses, and cross-correlation coefficients between drug pairs. From 2016 to 2023, total procurement of oral hypoglycemic drugs by Shanghai healthcare institutions increased from 346.71 million DDDs to 476.15 million DDDs. Sulfonylureas, biguanides, and α-glucosidase inhibitors are ranked as the top three categories. SGLT-2 inhibitors, fixed-dose combinations, and DPP-4 inhibitors showed the fastest growth. Among the 16 policy-covered drugs, the procurement volumes of bid-winning products for metformin extended-release, saxagliptin, acarbose, and canagliflozin increased significantly following policy implementation (Cohen’d > 0 or p < 0.01). Additionally, significant procurement changes were observed in potentially clinically substitutable drugs corresponding to acarbose, vildagliptin, canagliflozin, and empagliflozin (Cohen’d > 0 or p < 0.01). CCA showed time-lagged temporal associations between declining procurement of some traditional agents and increasing procurement of newer drugs or new formulations ( p < 0.001), suggesting broader pattern shifts in oral hypoglycemic drug procurement during the study period. From 2016 to 2023, the procurement volume of oral hypoglycemic drugs in Shanghai increased steadily. Following the implementation of the NCDP policy, heterogeneous changes were observed in the procurement volume and patterns of policy-covered drugs and their potential alternatives. These findings suggest that future policy implementation should monitor unintended shifts in procurement patterns and promote the rational use of oral hypoglycemic drugs.