We aimed to explore concomitant orally administered antidiabetic agent (OAD) regimens used in basal supported oral therapy (BOT) with insulin glargine in a real-life setting, and to assess the efficacy and safety of each regimen using data from the Add-on Lantus® to Oral Hypoglycemic Agents 2 study, a 24-week observational study in Japanese type 2 diabetes patients. Among 1629 insulin-naïve patients who had a glycosylated hemoglobin (HbA1c) value of ≥6.5% during the previous 4weeks and were treated with BOT during the observational period, 1227 patients who retained the same concomitant OAD regimens throughout the period were included in the analysis. Sulfonylurea (71.5%), dipeptidyl peptidase-4 inhibitor (DPP-4i; 60.7%), and biguanide (BG; 48.6%) were commonly administered OADs in BOT. The HbA1c level decreased in patients taking BG alone (-2.76%) and DPP-4i alone (-2.46%). Of the three OADs, mean doses of the most frequently administered OAD changed from baseline to the final evaluation point: 2.5-2.3mg for glimepiride, 59.1-58.7mg for sitagliptin, and 1145.6-1168.2mg for metformin. No significant difference in the hypoglycemia incidence rate was found between regimens (p=0.3765), with incidence rates of 1.9% (DPP-4i alone) to 7.0% (other regimens) observed. DPP-4i plays a major role in BOT with insulin glargine in a real-life setting. The incidence of hypoglycemia did not differ significantly between BOT regimens, including DPP-4i. Insulin glargine added to DPP-4i is a potential therapeutic approach.