The European Medicines Agency is investigating reports that India’s Wanbury Pharma, one of the largest exporters of the diabetes drug metformin, had more than half of its exports produced by an unlicensed supplier.

India’s export certificate for Wanbury was issued after a June inspection by the Maharashtra Food and Drug Administration. However, MFDA later found Wanbury had export orders of 650 metric tons per month, but only had the capacity to manufacture 300 tons.

To make up the shortfall, Wanbury outsourced the manufacturing of metformin to Pharmaceutical Products of India (PPIL), which did not have an export license. Wanbury put its own label on the product and exported it.