Aims: The study was designed to examine potential long term effects on glycemic control and treatment satisfaction in people with diabetes type 1 who changed from multiple daily insulin injections (MDI) to insulin pump (CSII). Methods: Forty-six patients who changed from MDI to CSII were recruited at a Swedish medical clinic. They were followed one year prior to starting CSII and four years afterwards. Repeated measurements of HbA1c were performed during follow-up. Treatment satisfaction was assessed using Bradley’s Diabetes Treatment Satisfaction Questionnaire, status version. Results: After initiation of CSII, reductions of HbA1c were seen after the first year (0.66 units of percent [95% Cl, 0.46-0.91]) and after 2-4 years, (0.65 [95% Cl, 0.38-0.95]). Moreover, treatment satisfaction increased significantly after six months (10.0 score units [95%.CI, 8.0-12.0]) and remained at the same level after three years, (10.5 score units [95%.CI, 8.0-13.0]). Conclusions: Compared to MDI, insulin pump therapy improves glycemic control with sustained treatment satisfaction after up to 4 years. Our long term data provide further support for CSII as an effective and well tolerated treatment regimen for patients with type 1 diabetes.