Background and Objectives: Diabetes monitoring requires repeated invasive methods. Saliva is a rich source of biomarkers without the need for an invasive method for its collection. Sialic acid is proposed as an acute-phase protein in chronic inflammation of diabetes. This study aimed to determine the association between total salivary sialic acid (TSA) and HbA1c and fasting blood sugar (FBS) in prediabetic and type 2 diabetic individuals, and to evaluate its potential diagnostic utility as a non-invasive biomarker for differentiating these two groups.
Methods: This cross-sectional study was carried out on 70 participants (34 with prediabetes, 36 with type 2 diabetes) who were referred to Shahid Moffateh Clinic, Yasuj, Iran. Convenience sampling was employed. Unstimulated saliva (spitting method) and fasting venous blood samples were obtained. TSA was assessed by spectrophotometry, whereas HbA1c and FBS were measured using standard biochemical methods. Data were analyzed with SPSS 23 using Spearman/Pearson correlation tests.
Results: Mean age of participants was 50.38±10.14 and 51.50±9.13 years in prediabetic and diabetic groups, respectively. Mean FBS (mg/dL), HbA1c (%), and TSA (mg/dL) levels in prediabetics were 108.94±9.04, 5.63±0.246, and 1764.7±742.02, and in diabetics were 167.05±55.83, 7.02±1.67, and 1672.51±576.59, respectively. No significant correlation was found between TSA and FBS (P=0.53 for prediabetic, P=0.19 for diabetic) and TSA and HbA1c (P=0.90 for prediabetic, P=0.62 for diabetic) in either group. The ROC curve area was 0.44 (P=0.38), indicating poor diagnostic power.
Conclusion: Based on our findings, total salivary sialic acid is not a suitable biomarker to replace HbA1c for monitoring prediabetic and type 2 diabetic individuals. Further studies investigating other salivary biomarkers or free sialic acid are recommended.