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.