Background: The different systems for monitoring capillary blood glucose levels may suffer interference from various substances.
Case report: Male patient, 48 years old, with history of hypertension, dyslipidemia and previous smoking. He presented also type 1 diabetes mellitus, with 37 years of progress, with diabetic retinopathy, kidney failure, in peritoneal dialysis since 2009, and ischemic heart disease (myocardial infarction in 2005). He was treated with insulin, angiotensin receptor antagonists, beta blockers, calcium channel blockers, darbepoetin, metolazone, loop diuretics, aspirin, proton pump inhibiters, folic acid. Because of glycemic instability, with frequent hypoglycemic events, he was proposed for therapy with insulin infusion pump. As an inpatient, at the time of therapy adjustment with insulin pump, he frequently referred symptoms suggestive of hypoglycemia. However, determinations of capillary glycaemia (CG) with test strips based on glucose dehydrogenase-PQQ method revealed persistently high glucose levels. At the 4th day of hospitalization, capillary glycaemia determinations were performed simultaneously with test strips based dehydrogenase-PQQ method and with test strips based glucose oxidase method. A significant difference, of about 100 units, was found between the two values (dehydrogenase-PQQ method CG=147 mg/dl; glucose oxidase method CG=45 mg/dl).
Conclusions: Some sugars, such as maltose, interfere with blood glucose monitoring systems based on dehydrogenase-PQQ method. This interference occurs solely through the use of maltose in preparations administered parenterally or used in peritoneal dialysis. Maltose administered orally does not interfere with the determinations of the CG. Thus, CG determination by test strips based on glucose dehydrogenase method should not be used in patients on peritoneal dialysis using solutions containing isodextrin, which has maltose as an intermediate metabolite.