By Andrew Zajac

Abbott Laboratories Wednesday announced a recall of as many as 359 million glucose test strips used to monitor diabetics’ blood sugar because they may give falsely low readings.

The strips may not absorb enough blood quickly enough to give a proper reading, which can lead users to try to raise sugar levels unnecessarily, or to fail to treat elevated glucose levels, the company said in a statement.

The chemically-treated paper strips were manufactured at an Abbott facility in the United Kingdom between January and May 2010, according to company spokesman Scott Davies. They were sold in the US and Puerto Rico in stores and online and also are used in health care facilities.

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 email.

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

While any inaccuracy in blood sugar readings is cause for concern for diabetics, “this is an error in a safer direction, falsely low rather than falsely high,” said Michael Thompson, a diabetes researcher and associate professor of medicine at George Washington University in Washington.

A false high reading could lead diabetics to overdose on insulin, triggering a dangerous hypoglycemic episode. “This isn’t going to do that,” Thompson said.

Davies said that both the number of customer complaints about the quality of the strips and the number of reports of adverse medical events have been within the expected range for the volume of strips in the market.

Davies said it was inappropriate to speculate about medical harm, if any, from defective strips.

Abbott investigators have not determined the source of the defect, but are looking at storage conditions as a possible cause. Strips exposed to warm weather or held in prolonged storage may be more likely to yield false results.

The  recall involves 359 lots of strips marketed by Abbott’s Alameda, Calif-based Abbott Diabetes Care unit and are used with Abbott’s Precision Xtra, Precision Xceed Pro, MediSense Optium, Optium, Optium EZ and ReliOn Ultima blood glucose monitoring systems. The monitors, which read blood sugar levels in blood collected in the strips, are not affected by the recall, nor are other Abbott diabetes products.

Consumers can still use compatible test strips from lots that have not been recalled.

Davies said the affected lines of Abbott test strips make up about five percent of the U.S. market for such products.

Competing monitoring systems are made by Johnson & Johnson, Becton & Dickinson and Roche, among others.

Abbott customers can check if they have strips from affected lots by visiting www.precisionoptiuminfo.com, or by calling 1-800-448-5234 (English) or 1-800-709-7010 (Spanish) for more information.