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

Area of Science:

• Clinical Chemistry
• Laboratory Medicine
• Diabetes Diagnostics

Background:

• Accurate glycemic control assessment is vital for diabetes management.
• Pre-analytical variables, such as glycolysis inhibitors in blood collection tubes, significantly impact diagnostic accuracy.
• Current World Health Organization (WHO) criteria for diabetes classification rely on precise glucose measurements.

Purpose of the Study:

• To evaluate the impact of different glycolysis inhibitors in blood collection tubes on the classification of glycemic control.
• To assess the influence of tube selection on patient categorization according to WHO diabetes criteria.
• To quantify the potential misclassification of patients due to pre-analytical variations.

Main Methods:

• Glucose and lactate levels were measured in parallel using various blood collection tubes (Sarstedt and Greiner).
• Bias was determined relative to baseline conditions using fluoride heparin (FH) tubes with centrifugation within 1 hour.
• Sample stability and glycolysis inhibition effectiveness were assessed over 48 hours.

Main Results:

• Fluoride/EDTA/citrate (FC) tubes showed approximately 13% higher glucose and 20% lower lactate concentrations compared to FH tubes and serum.
• While glucose recovery was high (99-101%) over 48 hours, glycolysis inhibition by FC tubes was inconsistent.
• A mean bias of 12% with FC tubes could lead to an estimated 48.4-55.8% increase in patients classified with impaired glucose levels.

Conclusions:

• Using current WHO criteria, inconsistent glycolysis inhibition in FC tubes can substantially increase the number of patients identified with impaired glucose levels.
• This overestimation impacts patient treatment and resource utilization.
• Due to unpredictable failures, adjusting decision limits for FC tubes is not feasible; measuring glucose in FH tubes is recommended in the absence of outcome studies.