Plasma Glucose Concentrations in Different Sampling Tubes Measured on Different Glucose Analysers

Area of Science:

• Clinical Chemistry
• Analytical Chemistry
• Endocrinology

Background:

• The German Diabetes Association recommends citrate and fluoride additives in sampling tubes to inhibit glycolysis during oral glucose tolerance tests for diabetes diagnosis.
• The impact of different blood collection tubes on glucose measurement accuracy requires thorough investigation to ensure reliable diagnostic outcomes.

Purpose of the Study:

• To assess the effect of different sampling tubes with citrate/fluoride additives on glucose measurement results.
• To verify the impact of tube additives and incubation times on glucose concentrations across different analytical platforms.

Main Methods:

• Two studies involving participants undergoing oral glucose tolerance tests were conducted.
• Venous blood samples were collected in tubes with citrate/fluoride, citrate buffer, or lithium-heparin additives.
• Glucose measurements were performed on plasma samples after varying incubation times (<5 min, 20 min, 4 h) using different analyser models.

Main Results:

• Citrate/fluoride tubes generally inhibited glycolysis, with one tube showing results similar to baseline.
• A different citrate/fluoride tube exhibited significantly lower glucose concentrations on one analyser, a bias not observed on another model.
• Lithium-heparin tubes showed systematically lower glucose concentrations when centrifuged after 20 min or 4 h.

Conclusions:

• Citrate/fluoride sampling tubes are effective in inhibiting glycolysis for accurate glucose measurements.
• A negative bias in glucose measurements was observed with a specific citrate buffer tube on one analyser model, highlighting the importance of analyser-tube compatibility.