Pregnancy diabetes: A comparison of diagnostic protocols based on point-of-care, routine and optimized laboratory conditions

Abstract

In vitro glycolysis poses a problem during diabetes screening, especially in remote laboratories. Point-of-care analysis (POC) may provide an alternative. We compared POC, routine and STAT analysis and a feasible protocol during glucose tolerance test (GTT) for pregnancy diabetes (GDM) screening. In the routine protocol, heparin tubes were used and turn-around-time (TAT) was unsupervised. In the STAT protocol, tubes were processed immediately. The feasible protocol comprised of citrated tubes with a TAT of 1 hour. Outcome was defined as glucose concentration and clinical diagnosis. Glucose measured by POC was higher compared to routine analysis at t = 0 (0.25 mM) and t = 120 (1.17 mM) resulting in 17% more GDM diagnoses. Compared to STAT analysis, POC glucose was also higher, although less pronounced (0.06 and 0.9 mM at t = 0 and t = 120 minutes, respectively) and misclassification was only 2%. Glucose levels and clinical diagnosis were similar using the feasible protocol and STAT analysis (0.03 mM and −0.07 mM at t = 0 and t = 120, 100% identical diagnoses). POC is an viable alternative for STAT glucose analysis in GDM screening (sensitivity: 100%, specificity: 98%). A feasible protocol (citrated phlebotomy tubes with a TAT of 60 minutes) resulted in 100% identical outcome and provides the best alternative.

Accuracy of five plasma calibrated glucometers to screen for and diagnose gestational diabetes mellitus in a low resource clinic setting

“…Glucometers measured higher blood glucose concentrations than the laboratory at all time points of the OGTT. In a previous report comparing the diagnostic accuracy of a glucometer, routine analysis and an optimized laboratory, glucometer results approximated the optimized laboratory, however, the routine laboratory underdiagnosed GDM positive states [11]. It is known that blood glucose concentration drops by approximately 5–7% per hour ex vivo due to ongoing glycolysis, and sodium fluoride does not necessarily negate this effect within the first four hours [9].…”

Effects of different tube types on patient classification using current diabetes decision limits

“…Published guidelines propose in addition to immediate centrifugation an immediate storage of samples in an ice/water slurry for a maximum of 30 min to minimize glycolysis [4]. Although glycolysis is slower at cold temperature, it cannot be stopped completely, and inter-individual glycolytic rates vary [[20], [21], [22]]. Handling of samples in an ice/water slurry is not practical and is therefore not well accepted under routine conditions [23].…”

Diagnosis of Gestational Diabetes Mellitus with Point-of-Care Methods for Glucose versus Hospital Laboratory Method Using Isotope Dilution Gas Chromatography-Mass Spectrometry as Reference

“…Journal of Diabetes Research clinical setting, in a rather large number of women at a high risk of GDM using WHO 2013 diagnostic thresholds. Previous studies have shown no or only a small increase in the diagnoses of GDM with the use of lyophilized citrate tubes [22,24]. However, these studies were based on smaller numbers of women with generally lower glucose levels and few patients close to the diagnostic cut-off levels.…”

“…Other groups have reported a small positive bias for glucose concentrations measured in citrate buffer tubes when compared to glucose values measured in conventional tubes under optimal preanalytical conditions [16,20,21]. However, still other groups have reported good agreement in glucose results between the different types of collecting systems [22][23][24]. A suboptimal inhibition of glycolysis in the reference tube may account for some of these differences, considering that glycolysis takes place within minutes from venipuncture until plasma is separated [20].…”