Materials and methods. In this study two hundred patients were recruited from the diabetes clinic in Mustafa Khomeini Hospital in Tehran, Iran. OHRQL was assessed using Oral Health Impact Profile Questionnaire (OHIP-20). Also, another questionnaire was designed which contained questions regarding participants’ knowledge about oral complications of diabetes and oral health behavior. OHRQL was categorized as low and good. Data were analyzed using logistic regression at P = 0.05. 

Results. Of the diabetic patients assessed, 77.5% were in good and 22.5% were in low categories of OHRQL. This quality was significantly associated with age (OR = 4.03, 95% CI = 1.63‒11.29), knowledge about diabetes oral complications (OR = 18.17 95% CI = 4.42‒158.6), educational level (OR = 26.31 95% CI = 4.2‒1080.3), referred for dental visit by physician (OR = 3.16 95% CI = 1.48‒6.69), frequency of brushing (OR = 10.29 95% CI = 3.96‒31.2) and length of time diagnosed with diabetes (OR = 6.21 95% CI = 2.86‒13.63). 

Conclusion. Oral health related quality of life was not negatively affected by diabetes mellitus in the assessed sample.