Abstract Disclosure: H. Jang: None. Background: Overbasalization, which refers to adjusting the dose of basal insulin beyond an appropriate dose, should be avoided when using basal insulin in patients with type 2 diabetes. It is recommended to evaluate overbasalization when the basal insulin dose exceeds 0.5 units/kg/day or when post-meal glucose levels are > 180 mg/dL. However, this is an expert opinion, and specific criteria for East Asians have not been presented. Methods: Patients with type 2 diabetes using basal insulin (insulin glargine U-100, insulin glargine U-300, insulin degludec, NPH) at Seoul National University Bundang hospital from December 2020 to November 2023, with fasting plasma glucose (FPG) levels between 80 mg/dL and 130 mg/dL, were retrospectively analyzed. Patients with CKD ≤ grade 3b (estimated glomerular filtration rate < 45 mL/min/1.73m2), those taking medications such as steroids that may affect blood glucose levels, and patients undergoing cancer treatment were excluded. Results: A total of 548 patients were analyzed. The mean age of the subjects was 64.7 ± 12.4 years, with 299 (54.6%) being male, and the mean body mass index was 25.1 ± 6.6 kg/m2. The mean duration of diabetes was 18.1 ± 9.6 years. The mean HbA1c level was 7.7 ± 1.1%, while the mean fasting plasma glucose and median fasting C-peptide levels were 105.4 ± 13.9 mg/dL and 1.4 [0.8, 2.1] ng/mL, respectively. Insulin degludec being the most commonly administered (279 [50.9%]). The mean 2-hr postprandial glucose was 206.3 ± 64.8 mg/dL, with 350 (63.9%) having 2-hr postprandial glucose > 180 mg/dL. The administered insulin dose was 0.35 ± 0.17 units/kg/day, and 101 (18.4%) had an insulin dose > 0.5 units/kg/day. Conclusion: In East Asian patients with type 2 diabetes receiving basal insulin, although high 2-hr postprandial glucose levels suggest the possibility of overbasalization, the administered dosage of basal insulin was relatively low. Considering the lower insulin secretion capacity in East Asians, it is thought that new, specific criteria for overbasalization in East Asians are necessary. Presentation: 6/3/2024