OBJECTIVES: Depression prevalence among diabetes patients is reported to be relatively high. It is also reported the comorbidity of depression among the diabetes patients might worsen glycemic control. However, the measures against depression for diabetes patients seem to be not enough in Japan. We examined depression prevalence in type 2 diabetes and the association with some factors to help prevent diabetes progression and depression prevalence.  METHODS: Data source was a Japanese employee based health insurance claims database containing company employees and their families. We used data having HbA1c in annual health checkup in 2014. Patients with type 2 diabetes and depression were identified by ICD10 codes. The patients undergoing diabetes treatment were defined as those prescribed diabetes drugs. The depression prevalence was analyzed in the patients and the others. Since the database contained fewer patients aged >60, we extracted the type 2 diabetes patients aged ≤60, then conducted logistic regression analysis of the association of depression prevalence with HbA1c, age, sex and diabetes treatment. RESULTS: Study population was 347,300 and type 2 diabetes prevalence was 11%. Depression prevalence rates in the patients and the others were 6% and 3%, respectively. The prevalence was higher in the patients than in the others in all age and sex groups. The depression prevalence in type 2 diabetes patients aged ≤60 associated with HbA1c [odds ratio (OR) =1.228, p=0.0003], age [OR=1.028, p<0.0001] and diabetes treatment [OR=1.263, p=0.0008], and without sex. CONCLUSIONS: We found the depression prevalence among type 2 diabetes patients was higher than in the others. There was positive association between HbA1c and depression prevalence; therefore, poor glycemic control probably may involve in depression prevalence. Because diabetes treatment seems to associate with depression prevalence, some measures considering comorbid depression should be required as well as glycemic control for type 2 diabetes patients.