The diagnostic performance of salivary gland shear wave elastography to differentiate Sjögren disease from type 2 diabetes mellitus with sicca: a cross-sectional controlled study

BACKGROUND: Xerostomia is a shared clinical manifestation of both Sjögren disease (SjD) and type 2 diabetes mellitus (DM), but their underlying pathophysiology differs markedly. The differentiation between autoimmune glandular damage and metabolic dysfunction is of clinical significance. This study aimed to evaluate the diagnostic performance of shear wave elastography (2D-SWE) for discriminating SjD from DM patients with sicca symptoms. METHODS: This cross-sectional study included three groups: 61 patients with SjD, 42 patients with type 2 DM presenting with sicca symptoms, and 43 age-matched healthy controls (HC). All participants underwent bilateral parotid and submandibular gland ultrasonography. Parenchymal inhomogeneity was graded using the Outcome Measures in Rheumatology (OMERACT) scoring system, and tissue stiffness (Young's modulus, kPa) was quantified via 2D-SWE. Pairwise comparison between groups were conducted, and the receiver operating characteristic (ROC) analysis was used to assess the performance of SWE in identifying SjD patients. RESULTS: The SjD group demonstrated higher stiffness values in the bilateral parotid and submandibular glands compared with both the DM and control groups. Additionally, the OMERACT total scores for all salivary glands were elevated in patients with SjD compared with the DM and HC groups (p < 0.001 for both groups). In contrast, the DM group exhibited tissue stiffness and gray-scale ultrasound profiles that were comparable to those of the HC group (p > 0.0167 for all comparisons). The ROC analysis indicated that SWE possessed moderate discriminatory power for distinguishing SjD from DM (Area Under the Curve (AUC) range for glands: 0.598-0.628). CONCLUSION: The combined use of SWE and gray-scale assessment may serve as a multiparametric approach that could contribute to differentiating autoimmune sialadenitis in SjD patients from metabolic sialosis in DM patients presenting with dry mouth.