Aim: Type 1 diabetes mellitus (DM1) is the most common chronic disease in children and adolescents. The purpose of this study was to determine the relationship between Type 1 diabetes mellitus and periodontal health and also the effect of metabolic control level on both periodontal and dental health. Material and Methods: A Total of, 152 patients, of which 76 subjects with type 1 diabetes (DM1) and 76 healthy individuals were participated in this study. The subjects were also categorized with regard to gender and metabolic control levels. Periodontal health was assessed by recording plaque index (PI), gingival index (GI), pocket depth (PD) and bleeding on probing (BOP); while the dental status was determined by Decayed, Missing and Filled Teeth index (DMFT). Results: All periodontal scores were found to be significantly higher in DM1 group, whereas DMFT scores were similar in DM1 group and healthy controls. The glycemic control levels did not seem to have an impact on periodontal parameters (PI, GI, PD, BoP) and DMFT scores. Also, there were no statistically significant correlations between periodontal parameters and DMFT scores, and HbA1c values. Conclusion: Diabetes seems to be associated with poor periodontal health status regardless of the metabolic control level in adolescents, but not with increased caries risk.