Importance of Blood Glucose Management Before¹⁸F-FDG PET/CT in 322 Patients with Bacteremia of Unknown Origin

Abstract

We investigated the effects of blood glucose levels on the performance of ¹⁸F-FDG PET/CT for detecting an infection focus in patients with bacteremia. <b>Methods:</b> A total of 322 consecutive patients with bacteremia who underwent ¹⁸F-FDG PET/CT between 2010 and 2021 were included. Logistic regression analysis was performed to evaluate the association between finding a true-positive infection focus on ¹⁸F-FDG PET/CT and blood glucose level, type of diabetes, and use of hypoglycemic medication. C-reactive protein, leukocyte count, duration of antibiotic treatment, and type of isolated bacteria were considered as well. <b>Results:</b> Blood glucose level (odds ratio, 0.76 per unit increase; <i>P</i> = &lt;0.001) was significantly and independently associated with ¹⁸F-FDG PET/CT outcome. In patients with a blood glucose level between 3.0 and 7.9 mmol/L (54–142 mg/dL), the true-positive detection rate of ¹⁸F-FDG PET/CT varied between 61% and 65%, whereas in patients with a blood glucose level between 8.0 and 10.9 mmol/L (144–196 mg/dL), the true-positive detection rate decreased to 30%–38%. In patients with a blood glucose level greater than 11.0 mmol/L (200 mg/dL), the true-positive detection rate was 17%. In addition to C-reactive protein (odds ratio, 1.004 per point increase; <i>P</i> = 0.009), no other variables were independently associated with ¹⁸F-FDG PET/CT outcome. <b>Conclusion:</b> In patients with moderate to severe hyperglycemia, ¹⁸F-FDG PET/CT was much less likely to identify the focus of infection than in normoglycemic patients. Although current guidelines recommend postponing ¹⁸F-FDG PET/CT only in cases of severe hyperglycemia with glucose levels greater than 11 mmol/L (200 mg/dL), a lower blood glucose threshold seems to be more appropriate in patients with bacteremia of unknown origin and other infectious diseases.

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