Usefulness of hemoglobin a1c and glycated albumin measurements for insulinoma screening: An observational case-control study

Insulinomarepresents hypoglycemiaas a predominant symptom; the autonomic symptoms may be resolved by chronically recurrent hypoglycemiaresulting in the persistence of non-specific symptoms alone. Therefore, it has been estimated that there are many patients in whom the disease takes longer to diagnose and has remained undiagnosed. Although some parameters exist for the definitive diagnosis of the disease, there are currently no indices for early screening. Indices of glycemic control, hemoglobin A1c (HbA1c), and glycated albumin (GA) may be useful for the screening of patients with insulinomahaving chronic hypoglycemiabecause the values become low in such a condition. Because there are no articles that have reported the point, we examine the effective cutoffvalues of HbA1c and GA for the diagnosis of insulinomain the present study. In a multicenter cross-sectional study, 31 patients with insulinomawere included for comparison with 120 control subjects with normal glucose tolerance based on 75 g oral glucose tolerance tests whose characteristics were matched to the patients. The primary outcomes were optimal cutoffvalues of HbA1c and GA for the screening of insulinoma. HbA1c was significantly lower in the insulinomagroup at 4.7 ± 0.4% compared to the healthy control group at 5.7 ± 0.3% (p < 0.001), and GA was significantly lower in the insulinomagroup at 11.6 ± 1.8% compared to the healthy control group at 14.5 ± 1.0% (p < 0.001). According to a receiver operating characteristic (ROC) analysis, optimal cutoffvalues of HbA1c and GA for the diagnosis of insulinomawere 5.0 and 12.4%, respectively. Area under the curve values of HbA1c and GA were 0.970 and 0.929, respectively, showing no significant difference (p = 0.399). In the present study, HbA1c and GA values in patients with insulinomawere significantly lower compared to the healthy controls, and effective cutoffvalues for screening were shown in the diagnosis of insulinomafor the first time. HbA1c and GA can be useful indices for insulinomascreening. Because malignant insulinomahave a similar diagnostic process to that of benign insulinoma, these could be useful for malignant insulinoma.