MRI-based volumetric and histogram analysis of parotid and submandibular salivary glands in type 2 diabetes mellitus: a retrospective study

Abstract Objective This retrospective study aimed to evaluate the MRI-based volumetric and histogram characteristics of the parotid and submandibular salivary glands in patients with type 2 diabetes mellitus (T2DM) compared with control participants, and to investigate potential correlations between gland volumes, HbA1c levels, and disease duration. Materials and methods Following approval from the Harran University Clinical Research Ethics Committee, magnetic resonance (MR) images of 30 patients with T2DM and 30 control participants were retrospectively analyzed. Salivary gland volumes were measured, and demographic data, HbA1c values, and diabetes duration were recorded for the T2DM group. In addition, histogram analysis was performed on T1-weighted MR images using standardized regions of interest to calculate mean grayscale values, skewness, and kurtosis parameters. Statistical analyses were conducted to compare gland volumes between groups and to assess correlations with clinical parameters. Results There were no statistically significant differences in the volumes of the parotid and submandibular glands between the T2DM and control groups ( p > 0.05). Additionally, no significant correlations were found between gland volumes and HbA1c levels or disease duration within the diabetic group. Patients with T2DM demonstrated significantly lower mean grayscale values across all major salivary glands compared with controls (all p < 0.01), whereas skewness and kurtosis values remained comparable between groups (all p > 0.05). Conclusion The findings suggest that T2DM was not associated with significant volumetric differences in the major salivary glands in this study population. However, significantly lower mean T1-weighted grayscale values were observed in patients with T2DM, whereas skewness and kurtosis remained comparable between groups. These signal-intensity differences should be regarded as exploratory imaging findings rather than direct evidence of specific microstructural alterations, and their functional and clinical significance remains uncertain. Further studies incorporating quantitative MRI techniques and functional correlation are needed to clarify their biological and clinical relevance.