Diagnóstico salivar de diabetes mellitus utilizando espectroscopia de reflexão total atenuada no infravermelho com transformada de Fourier (ATR-FTIR)

Abstract

Introduction: Monitoring of blood glucose is an invasive, painful and costly procedure in diabetes. Consequently, the search for more a cost-effective (reagent-free), non-invasive and specific diabetes diagnostic method is of great interest. Objective: This research investigated the application of ATR-FTIR spectroscopy as an alternative for the diagnosis of DM by quantitative salivary spectrum analysis. Material and methods: Wistar rats were divided in non-diabetic (ND), diabetic (D) and diabetic 6U-treated of insulin (D6U). DM was induced by an intraperitoneal injection (60 mg/kg) of streptozotocin (STZ). The animals were submitted to 28 days of diabetes, and on the 21st day, the treatment was started for 7 days with insulin or vehicle solution according to the group. Body weight, food and water intake, glycemia, urinary volume and urine concentration of urine were evaluated during the experiment. The salivary profile was analyzed by ATR-FTIR spectroscopy and the vibrational modes were evaluated for diagnostic ability by ROC curve. Results: Thirteen vibrational modes of saliva spectra of ND, D and D6U were identified, and of these, four vibrational modes were pre-validated as potential biomarkers for diagnosis by the ROC curve, with a significant correlation with glycemia. Compared to the ND, 1377 cm-1, 1255 cm-1, 628 cm-1 and 616 cm-1 bands of D rats gave a sensitivity and specificity of 100% (p<0.001). In addition, the spectral biomarkers 1255 cm-1 and 628 cm-1 demonstrated a high correlation with glycemia (R2 of 0.84 and 0.8595, respectively). Conclusion: Altogether, 1255 cm-1 and 628 cm-1 spectral salivary biomarkers may provide a novel robust alternative for diabetes diagnostics.