WINNIPEG -- Several batches of Metformin, a drug commonly used to treat diabetes, is being recalled.

Apotex Inc. is voluntarily recalling nine lots of its prescription metformin drug, APO-METFORMIN ER (extended release) 500mg tablets.

Test results from the company showed one of the lots (PY7174) contains a nitrosamine impurity called N-nitrosodimethylamine (NDMA) that increased over time to a level above the acceptable limit.

As a precautionary measure, the company is recalling eight other lots because levels of NDMA in those products may increase over time.

The lots were shipped on February 5.

In February, Ranbaxy Pharmaceuticals Canada Inc. recalled six lots of its prescription RAN-Metformin drug from the Canadian market for NDMA.

In March, JAMP Pharma Corporation recalled all 26 lots of its prescription Metformin drug from the Canadian market due to NDMA.

According to Health Canada, NDMA is classified as a probable human carcinogen.

People are exposed to low levels of nitrosamines everyday life through a variety of foods drinking water and air pollution. NDMA is not expected to cause harm when ingested at low levels.

Health Canada said a person taking a drug that contains NDMA at or below the acceptable level every day for 70 years is not expected to have an increased risk of cancer.

A full list of recalled metformin lots can be found here

Health Canada said individuals taking Metformin, including a recalled product, should not stop taking it unless they have spoken to their health care provider.