Purpose: Although rapid-acting insulins (RAIs) are used frequently in Korean clinical settings, evidence on their use is limited. This study explores the pattern and clinical effectiveness of the use of RAIs in Korean patients with type 2 diabetes mellitus (T2DM). Patients and Methods: This non-interventional, observational study enrolled patients (aged >18 years) with T2DM who were prescribed RAIs. The pattern of use and effectiveness of RAI analogs were evaluated over 6 months. Results: A total of 299/451 patients were analyzed. Approximately 90% (n/N=270/299) of the patients received insulin glulisine, which significantly reduced their levels of glycated hemoglobin (HbA1c: n=270, mean± standard deviation [SD]; -1.16±6.02%, p=0.0017), fasting plasma glucose (n=40; mean±SD: -54.9±90.89 mg/dl, p=0.0005), and post prandial blood glucose (n=35, mean±SD: -89.46± 105.68 mg/dl, p<0.0001) at 6 months, with a corresponding increase in body weight (BW) (n=197, mean±SD:1.45±3.64 kg, p<0.0001). At 6 months, more patients receiving an intensive regimen (basal insulin+≥2 RAI injections/day) had HbA1c <7% than those receiving a non-intensive regimen (basal insulin+1 RAI injection/day) (20.69% vs 7.46%; p=0.0333); the corresponding reduction in HbA1c was also higher in patients receiving the intensive regimen (p<0.0001). About one-fourth patients (n/N=22/95) were switched to the intensive regimen (from 1 to ≥2 RAI injections/day), and only 4.41% (n/N=9/204) of the patients were switched to 1 RAI injection/day. The patients receiving the intensive regimen showed higher levels of HbA1c reductions (mean±SD: -1.27±1.96%) compared with the maintenance group-1 RAI injection/day (mean±SD: -0.72±1.66%) (p=0.0459), without a significant increase in BW and body mass index. Conclusion: The insulin glulisine intensification regimen showed glycemic target achievement and can be considered a therapeutic tool in the management of T2DM patients.