Is antiglycolysis required for routine glucose analysis?

We obtained -68 pairs of simultaneously drawn serum and fluoride-oxalate plasma samples from patients and analyzed them by a continuous-flow (AutoAnalyzer II) glucose oxidase method. Glucose concentrations ranged from 370 to 3530 mg/L. Glucose concentrations for samples obtained in the fluoride-oxalate preservative averaged 42 +/- 35 mg/L (mean +/- SD) higher than serum. The magnitude of this difference was independent of glucose concentration. Linear-regression analysis of 270 pairs for which the time from collection to separation was recorded indicated that the difference between serum and plasma increased by 0.32 mg/L per minute of delay over a time span of 15 to 295 min. These differences are smaller than those described in standard textbooks. We conclude that, with the specimen-handling process used in our hospital, serum glucose determinations are clinically acceptable.