To explore glycemic control, and adverse events of Iranian people with uncontrolled type 2 diabetes after initiation of long-acting basal insulin, glargine. People with uncontrolled type 2 diabetes that was on at least two oral anti-diabetic drugs (OAD) were enrolled in this observational prospective study. Insulin glargine was prescribed by physicians in the course of routine clinical practice. Patients were followed for 24 weeks. Insulin doses were titrated to reach fasting blood sugar (FBS) target between 90 mg/dl and 130 mg/dl. HbA1c and adverse events were recorded at baseline, week 12, and week 24. Form a total of 292 participants, 243 patients completed the study. HbA1c, FBS, postprandial glucose, total cholesterol, triglycerides, and low-density lipoprotein cholesterol, but not body mass index decreased during the study. The proportion of poorly controlled patients (HbA1C>9%) decreased from 172 (58.9%) to 39(13.4%), and 21(7.2%) during follow up. Controlled glycemia (HbA1C