Changes in Soluble Serum CD81 Concentration during an Oral Glucose Tolerance Test in Patients with Diabetes Mellitus and Individuals with Normal Glucose Tolerance

Aim: Cluster of differentiation 81 (CD81) is a cell surface protein involved in cell development, activation, growth, and motility. Recent studies have suggested that CD81 is a marker of dedifferentiated beta-cells under conditions of metabolic stress, such as progressive diabetes. However, the clinical significance of changes in soluble serum CD81 (sCD81) in diabetic individuals remains unknown. The aim of this study was to investigate whether serum sCD81 concentrations differ between subjects with diabetes and normal glucose tolerance (NGT), and whether sCD81 changes during a 75 g oral glucose tolerance test (OGTT). Materials and methods: We recruited 101 subjects who had completed an OGTT. According to the test results, the participants were divided into diabetes mellitus (DM) and NGT groups. Participants with prediabetes were excluded from the analysis. During the OGTT, sCD81 levels were measured at 0 and 120 min. We compared changes in sCD81 between the groups. Results: In the DM group, soluble sCD81 levels were significantly higher at baseline and 120 min in the OGTT compared with the normal group (0.59 (0.22-1.05) ng/mL vs. 0.25 (0.81-0.67) ng/mL, 0.55 (0.17-0.96) ng/mL vs. 0.21 (0.92-0.78) ng/mL, p = 0.006 and 0.029, respectively). The soluble sCD81 levels in the NGT group remained unchanged (p = 0.658), while those in the DM group were significantly decreased during the OGTT (p = 0.003). Conclusion: Soluble sCD81 levels were elevated in individuals with type 2 diabetes, such that changes in sCD81 were only observed during the OGTT in the DM group. Soluble sCD81 may have potential as a new diagnostic marker for type 2 diabetes.