Comparison of Capillary and Venous Glucose Concentrations:A Real-world Study in Patients Undergoing Fluorodeoxyglucose-positron Emission Tomography

Objective Fasting capillary blood glucose(CBG)must be measured before fluorodeoxyglucose-positron emission tomography(FDG-PET)imaging.In this study,we aimed to investigate whether a recently measured fasting venous blood glucose(VBG)concentration could be substituted for CBG.Methods This retrospective study included 520 of 1,378 patients who had undergone FDG-PET at our institution in June 2022.None of the study patients had a history of diabetes mellitus.Each study patient’s CBG was measured immediately before FDG administration,whereas the VBG(VBG<7.8 mmol/L)was measured within one week before and after PET imaging.We used Bland−Altman plots to compare the two blood glucose concentrations.Results The 520 participants(315 male,205 female;ages 13-87 years)accounted for 37.7%(520/1378)of all patients.The median CBG and VBG were 5.7 mmol/L(interquartile range,5.2-6.2 mmol/L)and 5.1 mmol/L(interquartile range,4.8-5.8 mmol/L),respectively.There was a moderate positive correlation between CBG and VBG(r=0.4370,95%CI:0.3625-0.5059,P<0.0001).Bland-Altman plots revealed that only 5.8%(30/520)of the dots exceeded the 95%limits of agreement and these were all within acceptable limits,indicating that the bias was not clinically significant.Conclusion When performing FDG-PET on patients without diabetes,a VBG of<7.8 mmol/L within the previous week may be an acceptable alternative to CBG.