Objective The Japan Diabetes Society (JDS) has recommended target levels of glycemic control based on guidelines for the management of diabetes mellitus (DM). The Japan Society of Ningen Dock created a database of subjects receiving annual health examinations nationwide. Using this database, we evaluated the efficacy of current treatment for patients with DM based on the JDS recommendations. Methods This multicenter, retrospective study was conducted using data obtained from 21 institutions across Japan. In order to assess the level of glycemic control in the Japanese population, we analyzed previously obtained measurements of HbA1c in 7,180 patients 20 to 79 years of age (mean age: 57.9±8.7 years, 6,007 men and 1,173 women) taking DM medications. Results According to the JDS guidelines, 44.7% of the patients fell into the good glycemic control group, with an HbA1c level of <7.0% while 22.4% were classified into the poor glycemic control group, with an HbA1c level of ! 8.0%. The control of other arteriosclerosis risk factors deteriorated as the glycemic control deteriorated. Lifestyle factors were strongly found to be associated with glycemic control in the patients receiving DM treatment. Conclusion Aggressive lifestyle modification is needed to improve glycemic control in patients with DM.