Comparison of the Glucose Stability Effect Between Citrate-sodium Fluoride-EDTA, Heparin, and Sodium Fluoride Containing Tubes: A Prospective Experimental Study in the Biochemistry Laboratory at the University Clinic of Kinshasa, DR Congo.

Tubes containing sodium fluoride (NaF) are no longer recommended for measuring blood glucose levels. This prospective experimental study was conducted at the Biochemistry Laboratory of the University Clinics of Kinshasa, in the Democratic Republic of the Congo, and included seventy healthy volunteer blood donors. Glucose stability was assessed in tubes containing NaF, lithium heparinised tubes, and a tube containing a mixture of citrate, NaF and EDTA. The tubes containing citrate and NaF were stored at room temperature, whilst the corresponding heparinised tubes were placed on ice. Glucose measurements were taken at various time points (H0, H2, H24, H48) on centrifuged plasma kept in contact with blood cells. The citrate showed the highest and most stable glucose values over time, with virtually no loss of glucose. Lower glucose values were observed at H0 and H2 with the NaF (p < 0.05).Transporting the heparin tube on ice combined with centrifugation at +4°C resulted in higher blood glucose values than the NaF at time points H0 and H2 (p < 0.05), although lower than the citrate(p < 0.05);however, these values could not be maintained beyond 24 hours. Positive biases exceeding the desirable bias (1.8%) were observed between citrate and NaF tubes, as well as between heparinised and NaF tubes;this suggests a marked discrepancy and, consequently, a clinically significant difference between the various methods. For accurate blood glucose measurement, the citrate-NaF-EDTA tube is preferable in order to minimise glucose loss; however, a review of the diagnostic thresholds for diabetes mellitus must be carried out before its use. Cooling the sample is an effective alternative to compensate for the lack of citrate.