Introduction: Diabetes Mellitus (DM) is one of the common global health burdens. Measurement of blood glucose level is invasive and can cause many complications. Salivary glucose has been suggested as a suitable alternative for blood in recent years. The aim of this study was to establish the correlation between blood glucose level and salivary glucose level of type 2 diabetic mellitus patients. Methods: A cross sectional study was conducted at a diabetic clinic in a teaching hospital in Sri Lanka. Blood samples were collected to analyze fasting blood glucose and HbA1c levels. Unstimulated whole saliva samples were collected to measure salivary glucose level and salivary flow rate. Pearson’s correlation was applied to determine the association between salivary glucose, blood glucose and HbA1c levels. Results: A total of 120 type 2 diabetes mellitus patients and 31 healthy controls were participated. Salivary glucose level was significantly higher in DM patients than healthy individuals. Fasting blood glucose level was significantly correlated with salivary glucose levels among DM patients (r = 0.201, p = 0.027). A significant relationship was also observed between HbA1c and salivary glucose levels among DM patients (r = 0.288, p = 0.031). Conclusion: Measuring salivary glucose levels may have potential to be used as an alternative non-invasive procedure to screen, diagnose and monitor the glycemic conditions of the DM patients.