35.0% of participants brushed their teeth twice a day or more and 60.8% flossed rarely.The proportion of Hb A1c <7% was higher in three groups including the participants who had information about the effect of periodontal disease on diabetes (p= 0.032),participants who brushed twice a day or more (p= 0 .014), and those who used dental floss once a day or more (p< 0.001). This evidence concerns the gene GSTM1 and diabetes mellitus.