to assess salivary glucose correlation with blood glucose and its accuracy in diagnosis of diabetes and prediabetes.A comparative study including 204 adults in 3 groups (104 type 2 diabetics, 50 prediabetics, 50 non-diabetic controls) aging 18-65 years. The participants were interviewed about their socio-demographic, comorbidities,drug treatment using a predesigned questionnaire. Salivaryblood samples were collected and analyzed.Mean salivary glucose was observed to be 23.40 ± 12.755 mg/dl in control group, 42.68 ± 20.830 mg/dl in prediabetic group and 59.32 ± 19.147 mg/dl in diabetic group with significant difference between the 3 groups (P value 0.001). Salivary glucose was significantly correlated to FBS with strong positive association (r = 0.67, P value 0.001 in control group, r = 0.56, P value 0.001in diabetic group and r = 0.36, P value 0.01 in pre-diabetic group). Salivary glucose could differentiate non-diabetics from diabetics (AUC: 0.928, P value 0.001) with sensitivity (94.2%) and specificity (62%)differentiate non-diabetics from prediabetics (AUC: 0.928, P value 0.001) with sensitivity (94.2%) and specificity (62%).Salivary glucose estimation can serve as valid and non-invasive test for screening and diagnosis of diabetesprediabetes.