Introduction: The importance of saliva for oral health is well known. Diabetes mellitus affects the salivary gland functioning and thus alters the salivary constituents. For many years the question of the presence of glucose in saliva has been a subject of debate and only few people found correlation between serum glucose and salivary glucose in diabetics. Hence, the purpose of this study was to estimate and correlate salivary glucose concentration and serum glucose concentration in diabetics and healthy controls. Materials and Methods: 120 newly diagnosed diabetic patients and 120 control subjects were included in the study. Blood and saliva samples from both the groups were collected at least two hours after the breakfast. The samples were centrifuged and subjected to glucose analysis. For experimental group, the samples were collected again after the control of diabetes mellitus. The statistical comparisons were performed using paired and unpaired t–test. Results: A highly significant correlation was found between salivary glucose and serum glucose before the treatment and also after the control of diabetes. The correlation between salivary glucose and serum glucose was also highly significant in controls. it has an added advantage of being non–invasive procedure with no need of special equipments and with fewer compliance problems as compared with collection of blood.