https://www.ctvnews.ca/health/more-diabetes-drugs-recalled-over-contaminant-linked-to-cancer-1.4983576
There have been reports of unacceptable levels of nitrosamines in some of the metformin , slow release medication and there is a recall. It is not suggested that you stop taking your metformin, however it may be advisable to discuss this recall with your doctor or pharmacist.