Diabetes Mellitus is a disease that occurs when the blood glucose is too high. Saliva is a most valuable oral fluid. It is essential for alimentation, remineralization. of teeth, and the pharyngeal disorders and requires early diagnosis protection and lubrication of oral mucosal tissues. An unstimulated whole saliva flow rate in a normal person is 0.3-0.5 ml per minute, and below 0.1 ml per minute is significantly abnormal. The aim of the study is to estimate the salivary flow rate between prediabetic and uncontrolled diabetic patients. The subjects are asked not to eat or drink 30 minutes prior to beginning the collection of the saliva sample after swallowing all saliva they are asked to accumulate new saliva and discharge into the tube for every 60 seconds for a period of 5minutes. The saliva sample was collected from 25 Pre diabetic patients ranging from (80 to 130mg/dl) and 25 uncontrolled diabetic patients ranging more than 250mg/dl. The samples were selected from saveetha dental college. The collected in the graduated disposable syringe of 3ml and the reading was noted and analysed statistically. The salivary flow rate for uncontrolled diabetic patients is less than pre-diabetic patients. Salivary flow is required for normal metabolism. It gives protection to the oral cavity.