Objective: The objective of this study was to investigate the optimal blood pressure (BP) targets to prevent cardiovascular diseases (CVD) development in Korean subjects with type 2 diabetes mellitus (DM). Methods: Using the Korean National Health Insurance Service database, 2,262,725 subjects with type 2 DM who underwent regular health check-up from 2009 to 2012 were included. Patients with previous CVD were excluded. Patients were grouped by dividing the observed systolic BP (SBP) by 10 mmHg and diastolic BP (DBP) by 5 mm Hg. Results: There were 124,466 deaths (5.50%), 67,235 cases of stroke (2.97%), and 41,726 myocardial infarctions (MIs) (1.84%) during a median follow-up of 6.5 years. Compared with SBP 110-119mmHg, there is no increased risk among subjects with SBP 120~129 mm Hg but, SBP ≥ 130 mm Hg group was associated with a significant increment in the incidence of CVD. SBP 130~139 mm Hg group was associated with a significant increase in the incidence of stroke (hazard ratios [HR] 1.15, 95% confidence intervals [CI] 1.12-1.18) and MIs (HR 1.05, 95% CI 1.02-1.09), respectively, compared with the SBP 110-119 mmHg. Subjects with DBP 80-84 mmHg had a higher risk of CVD than subjects with DBP 75-79 mmHg. The overall relationship between BP and CVD risk was positive, with a greater strength observed for younger age groups (< 65 years old). Conclusion: The optimal cut-off for Korean diabetic patients to prevent increasing the risk of CVD may be around 130 mm Hg for SBP or 80 mm Hg for DBP. Younger aged patients with type 2 DM might benefit the most from attaining BP targets.