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

Background and aims: 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 degrees C) and the potential real-world impact of introducing these tubes on (gestational) diabetes and IFG prevalence. Materials and Methods: 25 healthy volunteers were sampled to assess glucose stability across time, at 4 degrees 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 K2C2O4 (NaFl) tubes) as well as with citrate-containing tubes (FC Mix). Results: 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 degrees C (3.1 %). The decrease reached 10.8 % (RT) and 7.8 % (4 degrees 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. Conclusions: Glucose concentrations rapidly decrease in NaFl tubes following collection and placing samples at 4 degrees C reduces only marginally the decay. Citrate-containing tubes offer a valuable solution for direct and longlasting glucose stabilization but, before wider adoption, large epidemiologic studies should confirm or redefine current diabetes diagnostic thresholds.