Comparison of Intranasal Saccharin Test and Intranasal Schirmer’s Test in Identifying Altered Nasal Mucociliary Clearance Time in Type 2 Diabetic Patients: A Cross-sectional Study

Introduction: Mucociliary Clearance (MCC) is an essential respiratory defence mechanism that is often impaired in patients with Type 2 Diabetes Mellitus (T2DM) due to hyperglycaemiainduced neuropathy and reduced nasal secretions. Identifying reliable methods to evaluate nasal function in patients with Diabetes Mellitus (DM) is crucial for the early detection of dysfunction. Aim: To compare the intranasal saccharin and Schirmer’s tests for assessing nasal MCC in patients with T2DM. Materials and Methods: This cross-sectional study was conducted in the Department of Ear, Nose, and Throat (ENT) at a tertiary care centre SRM Medical College Hospital and Research Centre, Chennai, Tamil Nadu, India, over a period of three months, from March 2025 to May 2025, involving 120 patients with T2DM aged 18-75 years. Patients underwent intranasal saccharin and Schirmer tests under standardised conditions. Data were analysed using descriptive statistics, Chi-square test, and Receiver Operating Characteristic (ROC) curve analysis by IBM Statistical Package for Social Sciences (SPSS) software version 25.0. A p-value <0.05 was considered significant. Results: The mean age of the participants was 57.70±12.08 years, and 66 (55%) were female. Prolonged Saccharin Transit Time (STT) (≥30 min) was noted in 91(75.8%) of patients, while reduced Schirmer’s test values (≤6 mm) were observed in 81 (67.5%) and normal values (>6 mm) in 39 (32.5%) patients. All patients with Schirmer’s values ≤6 mm [81 (100%)] had prolonged STT, whereas 29 (74.4%) of those with values >6 mm [39 (32.5%)] showed normal MCC. Schirmer’s test showed a sensitivity of 89.01%, specificity of 100%, Positive Predictive Value (PPV) of 100%, Negative Predictive Value (NPV) of 74.36%, and an overall accuracy of 91.67%. The ROC curve yielded an AUC of 0.997. Conclusion: Schirmer’s test demonstrated high sensitivity and specificity as a simple, non invasive screening tool for detecting nasal dysfunction in patients with DM. It may serve as a practical adjunct to the saccharin test in clinical practice, enabling the early recognition of MCC impairment in patients with T2DM.