The aim of this study was to appraise the influence of conventional periodontal treatment on metabolic control in Korean type 2 diabetic patients. In addition, their periodontal change was compared with non-diabetic patients. Before and after treatment, it was performed to measure periodontal and metabolic indices in thirteen type 2 diabetic patients. Periodontal indices included plaque index, gingival index, bleeding on probing, probing pocket depth, gingival recession, and clinical attachment level. Metabolic indices included glycated hemoglobin(HbA1c), fasting plasma glucose, fasting plasma insulin, total cholesterol, triglyceride, and HDL-cholesterol. Plaque index, gingival index, bleeding on probing, probing pocket depth, and gingival recession showed significant improvements in the statistics. Diabetic patients showed no statistically significant differences in the changes of periodontal indices compared with non-diabetic patients. HbA1c values decreased in five of the thirteen subjects and fasting plasma glucose levels were reduced in four of the seven subjects after periodontal treatment. All five subjects whom HOMA values were calculated in showed the increases of insulin secretions. The results of this study ascertained the possibility of the better glycemic contol after conventional periodontal treatment in Korean type 2 diabetic patients and diabetes were well healed of their periodontal diseases after the treatment.