Abbott Diabetes Care last week began recollecting defected blood glucose test strips in the U. S. and Puerto Rico. The affected test strips as many as 359 million may give false results, providing low blood glucose readings.

The strips may not soak up sufficient blood quickly adequate to give a proper reading, which can lead users to try to raise sugar levels unreasonably, or to fail to treat high glucose levels, the company said in a statement.

The chemically treated paper strips were invented at an Abbott facility in the United Kingdom between January and May 2010, according to company spokesman Scott Davies.

The defect came to light via routine in-house testing, Davies said.

North Chicago, Ill.-based Abbott reported 22 cases of "false low" readings to the Food and Drug Administration and volunteered to conduct the recall, FDA spokeswoman Erica Jefferson said in an e-mail.

The agency is "working with the company to determine if there may be additional instances where the readings were inaccurate," Jefferson said.

A false high reading could lead diabetics to overdose on insulin, triggering a dangerous hypoglycemic episode. "This isn't going to do that," said Michael Thompson, a diabetes researcher and associate professor of medicine at George Washington University in Washington. Consumers can still use well-suited test strips from bags that have not been recalled.