False measurement of glucose during dialysis with icodextrin]

Recent reports have indicated that icodextrin may interfere with glucose assays when patients are treated with icodextrin for peritoneal dialysis (PD). We wished to examine whether icodextrin interfered with plasma glucose, as measured with new instruments commonly used for glucose measurements in Norway.Serum and plasma glucose were measured in a diabetic patient (type II) who had started PD with icodextrin. Serum glucose was measured simultaneously in venous blood using the laboratory reference method (hexokinase), and compared with eight point of care testing (POCT) glucometers. The instruments used glucose dehydrogenase pyrroloquinolinequinone (GDH-PQQ), glucose dehydrogenase nicotinamide adenine dinucleotide (GDH- NAD), or glucose oxidase (GOx) methods.The laboratory reference method for glucose measurements was not affected by icodextrin. Biosensors with GDH-NAD and GOx methods did not give falsely elevated glucose results. Two of the eight POCT glucometers used the GDH-PQQ method. Both Ascensia Contour (Bayer HealthCare) and Accu-Chek (Roche Diagnostics) showed more than 60 % higher glucose values than the reference method.The GDH-PQQ method is non-specific for measurements of glucose. Over-estimation of glucose may result in unrecognized hypoglycaemia. POCT glucometers with a GDH-PQQ based monitoring system should not be used in diabetics receiving icodextrin for PD. The patients and caregivers must be informed about which glucometers to use.