Beginning in September, 2005, an ISMP Medication Safety Alert brought attention to the issue of inaccurate blood glucose readings in some monitoring systems. The FDA had previously issued a warning in July, 2005, and did so again several times over the next four years. They found that these devices, which had become a major tool for hospital personnel and outpatient treatment, could actually be extremely dangerous, if patients and practitioners were not educated in administration methods. They cited a specific example with an elderly patient who was given a high level of insulin after his blood sugar falsely read very high, which resulted in profound hypoglycemia, irreversible neurological damage, and death.
GDH-PQQ strips (glucose dehydrogenase pyrroloquinoline quinone) are blood glucose monitoring systems that use methodology that cannot distinquish between glucose and other sugars. Certain manufacturers use the substance maltose, a non-glucose enzyme, to measure blood and urine glucose. However, non-glucose enzymes are metabolized ‘in vivo’ and turned into maltose in the body, which creates a falsely elevated glucose result. The strips detect the presence of any sugars, even if they aren’t actually glucose, and then reads positive for glucose.
This misread can be life threatening for someone whose blood sugar is low but reads high, masking actual hypoglycemia, or if its normal but reads very high, causing the physician to treat it by administering unneeded insulin. So far there have been 18 deaths between 2002-2008 and likely many others that were not reported.
Those at risk include patients who use GDH-PQQ strips, were hospitalized, or are receiving one or more products containing non-glucose sugars (common to dialysis patients or those with other serious conditions or taking immunoglobulins). Unfortunately, many hospitals and health facilities use GDH-PQQ glucose test strips. The FDA suggests using only laboratory-based glucose assays on patients receiving the following products:
Extraneal (icodextrin) peritoneal dialysis solution 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 metablized into maltose, galactose or xylose
*Some non-specific reagents are used in patients taking xylose and galatose, which are found in some herbs, dietary supplements, and foods.
Dr. Jerry Sigel, who instituted an experiment on the issue, says that the problem has been known for nearly a decade, and there’s nothing in the literature that quantified it or even showed where the break points are. He says that when he used GDH-PQQ ezyme systems, the maltose at concentrations of 50mg/dL or more yielded falsely elevated plasma glucose values, whereas the FAD (glucose specific enzyme) had no effect on the glucose reading. He says that physicians have to change their productions or change their glucose meters, they cannot use the two together. He thinks it would be safer to monitor glucose without using maltose, but also acknowleges that it is unrealistic that drug companies are going to change their formulation; Cangene, a company that markets hyperimmune globulin products that interfere with glucose testing, says that they have no plans to change the formulations.
Dr. Sigel feels that the vast majority of doctors and nurses have no knowledge of this issue. He and other researchers strongly encourage the mantra, “treat the patient, not the glucose meter,” meaning, make sure that their symptoms are characteristic of someone whose glucose is actually at that level.