Insulinomas are rare pancreatic endocrine tumors characterized by hypoglycemia. Guidelines by the Endocrine Society (ES), the European (ENETS) and the North American (NANETS) Neuroendocrine Tumor Societies provide divergent diagnostic criteria. This study compared the diagnostic accuracy of these different criteria during the 72-h fasting test.
Retrospective cohort study.
From 2000 to 2014, 64 patients with a suspected insulinoma underwent a 72-h fasting test and were included in the analysis. This study assessed the diagnostic sensitivity, specificity and accuracy based on venous blood glucose and corresponding insulin levels measured by electrochemiluminescence immunoassay (ECLIA).
Based on 64 individuals (18 with, 46 without insulinoma), the ES criteria provided a diagnostic sensitivity of 0.94 (0.73–1.00), specificity of 0.89 (0.76–0.96) and accuracy of 0.91 (0.81–0.96). ENETS/NANETS criteria reached a diagnostic sensitivity of 0.78 (0.52–0.94), specificity of 1.00 (0.92–1.00) and accuracy of 0.94 (0.85–0.98).
These results point to a higher diagnostic sensitivity with less specificity for diagnosing insulinoma using ES criteria and a higher specificity at lower sensitivity by using ENETS/NANETS criteria. Before considering these results when applying the different criteria in clinical practice, the results should be confirmed in further studies comprising larger cohorts.
Supplementary Table 1: Diagnostic criteria for insulinomas
Supplementary Table 2: Individual data of the study cohort
Supplementary Table 3: Diagnostic accuracy of the guidelines’ criteria at the end of the fasting test
Supplementary Table 4: Diagnostic accuracy of insulin-glucose ratios of the entire study cohort (n=64)