Abstract: Objective: To evaluate xerostomia, salivary flow rate in diabetes mellitus patients and investigate it's relevance to history and metabolism. Methods: Type 1 diabetes mellitus (n=21) and type 2 diabetes mellitus (n=54) were selected, while healthy people with similar age and gender were chosen as control groups. Resting salivary flow rate was measured and xerostomia was evaluated by xerostomia questionnaire (XQ) in four groups. Results: Compared to control group, salivary flow rates of diabetes patients were decreased, but the decline degree in type 2 diabetes mellitus was small (P>0.05). Two diabetic mellitus groups complained xerostomia. OX scores were higher than those of control group (P<0.05). Salivary flow rate of type 2 diabetes mellitus was lower than type 1 diabetes mellitus and OX score was higher than that of type 1 diabetes mellitus (P>0.05). Sectionalized by HbA1C≤6% and history≤3 years (type 2 diabetes mellitus≤5 years), there was no difference in salivary flow rate and xerostomia between sectionalizations (P>0.05). Conclusion: Diabetes patients complain xerostomia obviously and their salivary flow rates decrease mildly compared to normal population. More attention should be paid in oral care for diabetes mellitus patients.