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

Abstract

Management of diabetes is a challenge starting in the pre-analytical phase with selecting the most appropriate glycolysis inhibitor. Study goal was to calculate the impact of tubes with different glycolysis inhibitors on the classification of the glycemic control of 157,415 consecutive hospital patients according to current WHO diabetes criteria.MethodsGlucose and lactate were measured in parallel in samples from 68 healthy subjects collected and stored in different sample tubes from Sarstedt and Greiner. Bias to baseline conditions (fluoride heparin (FH) tubes, centrifugation within 1 h) was determined.ResultsIn baseline samples, glucose concentration in fluoride/EDTA/citrate (FC) plasma was ~13% higher and lactate concentration ~20% lower compared to FH, fluoride oxalate, and fluoride EDTA plasma, and in serum. Glucose recovery after storage up to 48 h was 99–101% in the different tubes, but the effectiveness of glycolysis inhibition by FC was inconsistent. Based on the observed mean bias of 12% when FC tubes are used, we estimate an increase of 48.4–55.8% in the frequency of patients with impaired glucose levels using current WHO criteria.ConclusionUsing current established decision limits, the number of patients with impaired glucose levels in the hospital would increase substantially with a strong impact on patient treatment and consumption of resources. The unpredictable failure of glycolysis inhibition in FC tubes does not allow to adjust the decision limits by a fixed factor. In the absence of prospective outcome studies with FC tubes, we recommend to measure glucose in samples containing FH.

Age and sex dependent reference intervals for random plasma/serum glucose concentrations related to different sampling devices and determined by an indirect procedure with data mining

“…In the case that the presence of diabetes mellitus is suspected, further diagnostic procedures should follow according to international recommendations [3,4]. Independent of these recommendations, reevaluation of the decision limits for diabetes mellitus is postulated because the pre-analytic phase was not adequately considered when these limits were established [2]. Furthermore, it has been proposed [21][22][23] to lower the internationally recommended diagnostic decision limits [3,4].…”

“…In hospitals, it is required for detecting hypoglycaemia or hyperglycaemia which may occur due to several wellknown reasons. Observational studies have shown that hyperglycaemic patients with or without prior diagnosis of diabetes have an increased risk of complications and mortality, a longer hospital stay, and a higher admission rate to the intensive care unit [1,2].…”

“…These, called random (casual) glucose concentrations [3], are not considered to be suited for the diagnosis of diabetes mellitus, unless special pre-examination precautions are met. Whereas the reliability of the analytical (examination) part is well standardized, the pre-analytical (pre-examination) phase is still a matter of debate and of unsolved problems as recently summarized by Orth et al [2]. However, for asymptomatic persons, a hyperglycaemic value may be suspicious and may require further diagnostic procedures to confirm or rule out a possible diabetes mellitus [2].…”

“…Preanalytical factors for glucose measurement are challenging and both the patient preparation (fasting, physical activity, smoking, emotional stress, etc.) as well as the sample stability after blood drawing before and after centrifugation can impact glucose results in vitro and, therefore, the patient classification based on glucose testing results [2,4].…”

“…Lippi et al [12] recommended CFE tubes after having performed a literature overview because they were more efficient in preventing glycolysis and less prone to haemolysis compared to NaF blood tubes. However, Orth et al [2] found that CFE tubes often do not inhibit glycolysis sufficiently and pointed out that with CFE tubes, too many diabetic hyperglycaemias occur if the current internationally recommended decision limits are applied.…”