Background: Diabetes mellitus consists of a group of diseases characterized by abnormally high blood glucose levels. Glycated haemoglobin (HbA1c) is a form of haemoglobin used to identify the average concentration of plasma glucose over prolonged periods of time. It is formed in a non-enzymatic pathway by normal exposure of hemoglobin to high levels of plasma glucose, The main alterations observed in the saliva of Type 1 diabetic patients are hyposalivation and alteration in its composition, particularly those related to the levels of glucose. The aim of the present study was to assess the effect of Glycated haemoglobin level on the level of salivary glucose which may have an effect on oral health condition. Materials and methods: The total sample composed of 50 adults aged 18-22 years. Divided into two groups: 25 uncontrolled diabetes mellitus (HbA1c > 7), 25 controlled diabetes mellitus (HbA1c ≤ 7). Stimulated salivary samples were collected under standardized condition according to the criteria of Tenovuo and Lagerlöf (1994). Salivary glucose was estimated by using spectrophotometric analysis. The data were analyzed by using SPSS version 18 (Statistical Package for Social Sciences) to specify the statistical differences between the two groups. Results: the data of the present study assessed the correlation coefficients of HbA1c and salivary glucose and found that among uncontrolled diabetic group the relation between HbA1c and salivary glucose was significantly in positive direction (r = 0.483 p<0.05). While among controlled diabetic group, there was no relation between HbA1c and salivary glucose as the correlation coefficient was found to be equal to zero. Conclusion: the measurement of glycosylated hemoglobin, that is one of the well-established means of monitoring glycemic control in patients with diabetes mellitus, had a positive effect on the level of salivary glucose as its level increase with increasing the severity of diabetic disease