Stabilization of Plasma Glucose: The Use of Newer Technology and Pragmatic Laboratory Practice

The target values for plasma glucose concentrations for the investigation and diagnosis of diabetes and impaired fasting glucose, and the realization that small incremental changes in glucose concentration increase the risk of adverse events, has led to greater focus on laboratory glucose results. Although analytical methods show acceptable precision, the control of preanalytical error due to the stability of glucose remains problematic. The aim of this study was to compare glucose concentrations in 3 different and commercially available blood tubes, with analysis and storage under current practices and conditions.

Blood samples for glucose were obtained from consenting patients attending the Diabetic Clinic at the Royal Victoria Hospital, Belfast. Blood was collected into BD Vacutainer^® Barricor™ Lithium Heparin tubes, BD Vacutainer Fluoride EDTA tubes, and Greiner Vacuette^® FC-Mix (sodium fluoride/citrate/Na₂EDTA) tubes in that order. The Barricor tubes were immediately centrifuged at 4000g for 3 min. All samples were then sent to the Biochemistry Laboratory for analysis on the same day, and again the following day after storage at 4 °C.

There was no significant difference in mean glucose concentrations between immediately centrifuged Barricor and FC-Mix tubes when analyzed on day 0. Both tube types demonstrated higher mean glucose concentrations than traditional fluoride EDTA (F/EDTA) samples.

Both immediately separated Barricor and citrated FC-Mix plasma preserve glucose concentrations to the same extent, and better than F/EDTA preservative. These newer technologies involved offer pragmatic solutions to improved glucose analysis, allowing laboratories to choose the best option given the source of their samples.