How pre-analytical conditions impact glucose measurement and (gestational) diabetes diagnosis: A real-world stability study and a call for harmonization.

• Glucose concentration drops quickly before centrifugation in tubes containing only sodium fluoride (NaF). • Placing samples at 4 °C reduces only partially glucose decrease. • Citrate-containing tubes stabilize glucose concentrations for at least 24 h. • Mean bias between both tubes peaked between two- and four-hours following blood collection and reached 8.59%. • The use of citrate-containing tubes increased IFG, DM and GDM prevalences by 84.0%, 36.7% and 150%, respectively. Since 2023, guidelines of the AACC/ADA recommend the use of citrate buffer-containing tubes as a first option for glucose measurement. This study aims to assess the pre-analytical stability of glucose under various conditions (room temperature (RT) or at 4 °C) and the potential real-world impact of introducing these tubes on (gestational) diabetes and IFG prevalence. 25 healthy volunteers were sampled to assess glucose stability across time, at 4 °C and at RT, before and following centrifugation. 701 patients undergoing fasting plasma glucose analysis and 109 women having OGTT were collected according to current procedures (NaFl K 2 C 2 O 4 (NaFl) tubes) as well as with citrate-containing tubes (FC Mix). The mean glucose concentration bias between FC Mix and NaFl tubes when centrifugation occurred within 5 min was 0.53 % and this difference raised slowly to reach 2.3 %, six-hours post-centrifugation. When centrifugation was delayed, a rapid decrease in glucose concentrations was observed for NaFl tubes (4.9 % at 30 min) and this trend was only partially reduced by placing samples at 4 °C (3.1 %). The decrease reached 10.8 % (RT) and 7.8 % (4 °C) at 2 h, before reaching a plateau. Samples collected on citrate remained stable during 24 h. In real-life conditions, the mean bias between FC Mix and NaFl tubes increased progressively over time and reached 8.59 % for samples centrifuged between two- and four-hours following sampling. Compared to widespread practices, the use of citrate-containing tubes increased IFG, DM and GDM prevalences by 84.0 %, 36.7 % and 150 %, respectively. Glucose concentrations rapidly decrease in NaFl tubes following collection and placing samples at 4 °C reduces only marginally the decay. Citrate-containing tubes offer a valuable solution for direct and long-lasting glucose stabilization but, before wider adoption, large epidemiologic studies should confirm or redefine current diabetes diagnostic thresholds. [ABSTRACT FROM AUTHOR]