Polymedica

(PLMD)

said the SEC opened a formal investigation into its accounting practices and public disclosures.

The diabetes test-kit distributor previously disclosed the investigation as an inquiry, and has already said the U.S. attorney in Florida is investigating its Liberty Medical Supply unit for alleged billing fraud.

In a statement, Polymedica said it's cooperating with the SEC probe, which it said allows the commission to "obtain relevant information from third parties in addition to the company." The company denies the charges.