Background: This study aimed to determine long-term effect of intensive insulin therapy on prevention, progression, and development of chronic diabetes complications, both micro and macrovascular events. This study also aimed to evaluate long-term sustainability of glycemic control of patients on intensive insulin treatment. Methods: A retrospective review of adult type 2 diabetes mellitus (T2DM) patients on intensive insulin therapy for ≥7 years. Demographic data, co-morbidities, body mass index (BMI), hemoglobin A1c (HbA1c), hospitalization were collated. Majority received intensive insulin therapy with combination of premixed 70/30 given two times a day and fast short acting analogue given premeal three times a day, with the addition of glargine or degludec once a day in some. Results: Among 76 patients, 62% were males and 38% were females. Mean age at diagnosis and last visit were 53 and 65 years, respectively. At time of diagnosis, patient had the following co-morbidities: hypertension (32%), dyslipidemia (13%), non-dialyzable chronic kidney disease (CKD) (4%), thyroid disease (1%), pulmonary tuberculosis (1%). In terms of long-term complications, event rates during follow up period are as follows: 0.001 per person-year for acute coronary event; 0.002 per person-year for CKD needing dialysis, 0.009 per person-year for cerebrovascular accident. There were no blindness and amputation observed. There is a statistical difference between HbA1c levels at time of diagnosis (8.53 ± 1.86) and last follow up (7.83 ± 1.71) (P = 0.00). After a median follow up of 12 years (7–22 years), glycemic control was sustained with an HbA1c of ≤7% and ≤8% in 32% and 45% of patients, respectively. Conclusion: With intensive insulin therapy, micro and macrovascular complications can be prevented significantly. Long-term sustainability of glycemic control was also achieved.