FDA warning about certain glucose testing strips   (August 30, 2009)

The FDA recently issued an alert for people with diabetes and their caregivers, Advice for Patients: Serious Errors with Certain Blood Glucose Monitoring Test Strips.The warning applies to only certain people, and only to certain BG strips, those which use a technology called GDH-PQQ (glucose dehydrogenase pyrroloquinoline quinone). Such strips are made by Roche, Abbott, and HDI: a complete list of the affected meters is available at the FDA alert.

The concern is that if you are using GDH-PQQ test strips and are also taking drug products or therapies that contain certain non-glucose sugars (including maltose, galactose and xylose), these sugars will produce a falsely elevated glucose result: these strips measure BG levels using methodology that cannot distinguish between glucose and these other sugars.

And if you or your physician treat the high BG (for instance, with an extra dose of insulin), you could crash into hypoglycemia. Or, cases of true hypoglycemia might go untreated if the hypoglycemia were masked by the falsely elevated glucose readings. The FDA has received "13 reports of death associated with GDH-PQQ glucose test strips in which there was documented interference from maltose or other non-glucose sugars." Six of the 13 deaths have occurred since 2008. The label for several of the products clearly spell out the risk; for instance, the Orencia label states:

"Parenteral drug products containing maltose can interfere with the readings of blood glucose monitors that use test strips with glucose dehydrogenase pyrroloquinolinequinone (GDH-PQQ). The GDH-PQQ based glucose monitoring systems may react with the maltose present in ORENCIA, resulting in falsely elevated blood glucose readings on the day of infusion. When receiving ORENCIA, patients that require blood glucose monitoring should be advised to consider methods that do not react with maltose, such as those based on glucose dehydrogenase nicotine adenine dinucleotide (GDH-NAD), glucose oxidase, or glucose hexokinase test methods."

Is it likely that you are at risk?

First, you would not be risk if you are using other brands of BG strips: The unaffected methods are glucose oxidase, glucose dehydrogenase nicotine adenine dinucleotide (GDH-NAD), or glucose dehydrogenase flavin adenine dinucleotide (GDH-FAD).

Second, you have to be receiving one (or more) of the products that contain other non-glucose sugars. That's not too likely, unless you are on dialysis or taking drugs called immunoglobulins, or have other serious medical problems. The FDA webpage lists the following products that can cause problems with GDH-PQQ test strips:

* Extraneal (icodextrin) peritoneal dialysis solution
* Some Immunoglobulins: Octagam 5%, Gamimune N 5%, WinRho SDF Liquid, Vaccinia Immune Globulin Intravenous (Human), and HepaGamB
* Orencia (abatacept)
* Adept adhesion reduction solution (4% icodextrin)
* BEXXAR radioimmunotherapy agent
* Any product containing, or metabolized into maltose, galactose or xylose.

There also seems to be a third component to the risk: hospitalization. Apparently, some hospitals and other healthcare facilities are using GDH-PQQ glucose test strips. The FDA suggests using only laboratory-based glucose assays on patients receiving such products. It's my surmise (although not stated in the FDA's discussion) that some patients using these products may be on other types of BG strips at home, and having no problem. But if they were hospitalized somewhere that routinely uses GDH-PQQ glucose test strips, the problem would suddenly develop.

Thus, it would require a combination of three things to cause the problem: use of a GDH-PQQ BG strip, use of a product containing maltose, galactose or xylose, and hospitalization.

This interaction does bring back to mind one of my favorite aphorisms about diabetes: there are a hundred things that influence blood glucose levels, and we physicians know about 50 of them. Or now, let's make it 51.