Nostrum Laboratories has voluntarily recalled two lots of the diabetes drug metformin after the company found that the product contained unsafe levels of a nitrosamine.

The FDA, which classifies nitrosamine as a possible carcinogen, issued a guidance in October urging manufacturers to conduct risk assessments for potential nitrosamine impurities.

The agency has been investigating drugs found to contain nitrosamines since 2018, including metformin, “sartan” blood pressure drugs, ranitidine and other heartburn medications.

The Kansas City, Miss., drugmaker has not received reports of any adverse events linked to the impacted products, the agency said in its published notice of the recall.