Diagnosis of gestational diabetes mellitus – how should we measure glucose?

Gestational diabetes mellitus (GDM) is associated with adverse health outcomes for mother and child that can be reduced by treatment (1). GDM diagnosis is based on an oral glucose tolerance test (OGTT) requiring accurate glucose measurements, as small errors can have a major impact on GDM prevalence (2). A major source of pre-analytical error in measuring glucose is in vitro glycolysis, which can result in significant reduction of glucose concentration (5-7 % per hour) (3) . Guidelines recommend immediate centrifugation or the use of ice-water slurry pre-analytical storage containers to minimize glycolysis, but most laboratories use blood collection tubes containing anti-glycolytic agents instead for practical reasons. Sodium fluoride (NaF), which is widely used, allows continued glycolysis for up to fours hours, lowering the measured glucose (4). Conversely, acidification of the sample by addition of citrate buffer provides immediate inhibition of glycolysis but is not widely used .