The purpose of this study was to evaluate the association between glycated hemoglobin (HbA1c) and all-cause mortality in type 2 diabetes mellitus. We conducted a community-based prospective cohort study of 352 type 2 diabetic patients aged 30-92 who participated in a community diabetes complications screening program in Gokseng-gun, Jeollanamdo, Korea. HbA1c levels were categorized as ＜6.5%, 6.5-6.9%, 7.0-7.9%, 8.0-8.9% and ≥9.0%. Patients were followed up on for a mean of 6.9 years. The Cox proportional hazards model was used to evaluate the relationship between HbA1c levels and all-cause mortality. During the mean follow-up period of 6.9 years, 77 patients (21.9%) died. A J-shaped association was found between HbA1c and all-cause mortality, with the lowest mortality at 6.5-6.9% of HbA1c levels. Compared to patients with HbA1c of 6.5-6.9%, patients with ＜6.5%, 7.0-7.9%, 8.0-8.9% and ≥9.0% had an adjusted hazard ratio (95% confidence interval) for all-cause mortality of 1.71 (0.76-3.84), 1.23 (0.53-2.82), 1.32(0.51-3.44) and 2.66 (1.01-7.02), respectively. We found a J-shaped association between glycated hemoglobin and all-cause mortality in Korean type 2 diabetic patients.