High levels of the probable carcinogen NDMA have been found in the U.S. supply of the widely used diabetes drug metformin, according to testing done by the online pharmacy Valisure, which is pressing regulators for recalls.

Valisure’s testing found NDMA in 15 different types of metformin made by 11 drug companies, including Amneal Pharmaceuticals LLC, Ascend Laboratories LLC and Actavis Pharma Inc. The highest levels detected were in a batch made by Amneal, which had as much as 16 times the acceptable daily limit of NDMA, according to Valisure’s findings.

Continue reading article by Emma Court.

Photographer: Sara Hylton/Bloomberg