Screening and diagnostic procedures for gestational diabetes mellitus. Requirements of blood glucose measurement

The new German guidelines on gestational diabetes (GDM) and maternity directives have been amended to improve the diagnostic handling of outpatients and its quality management. Glucose should be measured only in venous plasma or in venous blood under the condition that a constant factor of 1.11 is used to convert concentrations in whole blood to the plasma equivalent. The use of capillary whole blood or plasma is excluded. For the first time the use of selected point-of-care testing (POCT) glucose systems is recommended as an alternative to medical laboratory methods if the measurement quality and quality control matches the legal requirements for laboratory methods according to the guidelines of the German Medical Council for quality assurance of laboratory medical investigations (RiliBA"K (Richtlinie der Bundesarztekammer zur Qualitatssicherung laboratoriumsmedizinischer Untersuchungen), e.g. maximum tolerated total error of +/- 15 % compared to reference method values and if they are CE labeled for screening and diagnostics of GDM. The advantages of POCT glucose testing are obvious: preanalytical mistakes are avoided and the glucose results are immediately available for the consultation of the pregnant women. Devices for self-monitoring of blood glucose are excluded from GDM screening. As inhibition of glycolysis in whole blood is insufficient by NaF alone it has been combined with citrate/citrate buffer for an immediate and nearly complete inhibitory effect during transfer to the laboratory.