Should we still collect blood glucose sampling in fluoride tubes? An evidence-based study

Excerpt

Blood glucose can be measured in serum or plasma. If serum is let to stand in contact with RBC, the glucose level falls due to the glycolytic process occurring in the cytoplasm of the RBC. Fluoride, which blocks the glycolysis cycle, is being used as an additive in blood glucose collection tubes for decades. The use of these tubes was suitable for blood collection when there was a long delay (4 h or more) in separation of serum following blood collection. Recently with the availability of gel serum separator tubes (SST), serum no longer remains in contact with RBC as soon as the specimen is centrifuged. We hypothesized that the use of fluoride tubes can be eliminated if the glucose levels in gel tubes and fluoride tubes show no significant difference within 1 to 2 h of centrifugation and then after separation from RBCs for up to at least 4 h. Earlier study has shown that glucose is stable for 48–72 h, when separated from the red cells [1]. Some studies have also reported that there was no difference in glucose values for blood samples collected in plain gel tubes and fluoride tubes that were separated within 2 h of collection [2, 3], but the sample size was a limitation for valid statistical inference. American Diabetes Association (ADA) no longer recommends the use of fluoride to control glycolysis [4]. …