OBJECTIVES: To assess the reduction of complications and costs with continuous subcutaneous insulin infusion (CSII) versus multiple daily injections (MDI) in uncontrolled type 2 diabetic patients (T2D) in the UK. METHODS: The incidence of diabetes-related complications was calculated based on the Core Diabetes Model. The population characteristics, the reduction of HbA1c, and insulin dose were based on the Opt2mise study (Reznik et al., Lancet 2014) (mean age 56 years (SD 9.6); mean diabetes duration 15 years (SD 0.75)). For a baseline HbA1c of 9.0%, the reduction in HbA1c was -1.1 % versus -0.4%, respectively, for CSII vs MDI. Costs were UK-specific and expressed in £2014. RESULTS: The diabetes-related complications were reduced with CSII. At 5 years, the incidence reduction in complications associated with eye diseases, renal diseases, ulcer/amputation and cardiovascular diseases were -24%, -26%, -19% and -10%, respectively, in favour of CSII. This equates to a cost reduction of 12% over 5 years per patient. End stage renal disease was delayed by 1 year, neuropathy by 1.08 years and amputation by 0.87 year, myocardial infarction and stroke by 0.81 and 0.71 year respectively. Insulin dose was reduced for patients on CSII from 122.1 IU to 96.5 IU per day with a cost saving of £2,169 per patient over 5 years. CONCLUSIONS: Improvements in HbA1c with a decrease in overall insulin requirements observed with CSII versus MDI, may offer important reductions in diabetes-related complications and associated costs in a UK setting for uncontrolled T2DM patients.