Nation-Wide Wastewater-Based Epidemiology Assessment of Metformin Usage in China: 2014-2020

Metformin, the unique first choice medicine for type 2 diabetes (T2D) in the US and Europe, was not widely adopted in China until recently. We measured metformin in wastewater samples, collected in major cities in China every 2 years from 2014 to 2020, to understand spatial and temporal trends of metformin use in T2D treatment in China. The estimated metformin use (mg/day/person) increased significantly from 1.6 +/- 1.8 in 2014 to 4.2 +/- 3.6 in 2016, then to 7.0 +/- 8.8 in 2018, and 9.2 +/- 9.0 in 2020. Metformin use increased nationally and in all seven geographical regions. Our findings reflect the broader uptake of metformin for treatment of T2D in China in accordance with expert recommendations. There was higher metformin use in the North than in the South of China, reflecting similar spatial trends in obesity rate in China. Wastewater analysis is likely to be a cost-effective way to monitor T2D treatment across China in the future.