Background <p>This study aimed to investigate the availability, prices, and affordability of nationally negotiated antidiabetic medicines in China.</p> Methods <p>This study collected monthly medicine usage data from 2018 to 2023 from the China Medical Economic Information Network (CMEI). The study focused on 12 nationally negotiated antidiabetic medicines included in the 2020 edition of the National Reimbursement Drug List for Basic Medical Insurance, Work-Related Injury Insurance, and Maternity Insurance. This study covered 804 public general hospitals in 31 provincial administrative regions in China, among which 537 (66.79%) were tertiary, and 267 (33.21%) were secondary. The adjusted World Health Organization and Health Action International methodology was used to conduct a longitudinal descriptive analysis of the availability and affordability of 12 nationally negotiated antidiabetic drugs in the investigated hospitals. Besides, prices are expressed as the defined daily dose cost (DDDc).</p> Results <p>From 2018 to 2023, the number of antidiabetic medicines with availability exceeding 50% increased from 1 to 5. The total availability of the 12 medicines was higher in tertiary hospitals than in secondary hospitals. The DDDc of the 12 medicines decreased substantially from baseline, with reduction rates ranging from 22.78% to 90.39%. Affordability improved progressively over the study period, with declines ranging from 43.43% to 97.52%. In 2023, 7 out of the 12 antidiabetic medicines were affordable for the population. However, rural residents had lower affordability of the medicines than urban residents.</p> Conclusions <p>The overall availability, affordability and DDDc of 12 nationally negotiated antidiabetic medicines improved from 2018 to 2023. However, the overall availability of most antidiabetic medicines in China remained at a low level (less than 50%). Therefore, further efforts should be made to sufficiently and equally benefit patients with diabetes.</p>