OBJECTIVE The aim of the present study was undertaken to correlate the glucose levels in saliva and blood of diabetic and healthy nondiabetic individuals and to determine the efficacy of saliva as a diagnostic tool. METHODS This was a case-control study. METHODS Forty-five patients previously diagnosed with diabetes mellitus and 45 healthy controls were included in the study. The patients and controls were asked to come to the clinic in the morning, after 8-10 h fasting. At that time, 5 ml of venous blood and unstimulated saliva was collected from both the groups, and 2 h after meal, again, venous blood and unstimulated saliva were collected. The saliva and sera from blood samples were subjected to glucose estimation. Saliva was collected in sterilized vials, and blood was collected in test tubes. Glucose estimation was done by oxidase-peroxidase method. METHODS Pearson's correlation coefficient, Student's t-test and paired t-test were used for statistical analysis. RESULTS Correlation coefficient values show that there is a significant positive correlation between fasting blood and fasting salivary glucose levels and postprandial blood and postprandial salivary glucose levels. CONCLUSIONS Salivary glucose level estimation can be used as a potential indicator in screening, diagnosis and monitoring of diabetes mellitus. Furthermore, it is an easy and noninvasive method.