OBJECTIVES: Poor glycaemic control is associated with increased risk of micro- and macro-vascular disease in type 2 diabetes (T2D) patients. Switching patients from metformin to Glucovance (combined glibenclamide/metformin) leads to improved glycaemic control in previously poorly controlled patients. No long-term studies have been performed that compare complication rates, mortality, and long-term costs in patients switched from metformin to Glucovance. A method was sought to link the effects on glycaemic control of switching from metformin to Glucovance to long-term complication rates and associated costs. METHODS: A validated model was used to quantify the improvements in life expectancy (LE), the changes in total lifetime costs (TC) associated with the improved glycaemic control seen with switching patients from metformin to Glucovance. Standard Markov modelling was used to describe the long-term incidence and progression of diabetes-related complications (angina, MI, stroke, heart failure, peripheral vascular disease, neuropathy, foot ulcer, amputation, renal disease, and eye disease). Probabilities of complications and HbA1c-dependent adjustments were derived from published studies. Switching from metformin to Glucovance lead to a 1% point improvement in HbA1c. Direct costs of diabetes complications and treatment with either metformin or Glucovance were projected over patients' lifetimes (discounted 5% p.a.). Costs of complications were retrieved from published sources. A French third party payer perspective was taken. A typical type 2 diabetes cohort (baseline age of 59) was simulated over a 30 years period. Exstensive sensitivity analysis was performed. RESULTS: Improved glycaemic control after switching from metformin to Glucovance lead to decreased incidence and progression of diabetes-related complications, with an increase in LE of 0.80 years, and reduction in TC/patient of €2,050. CONCLUSIONS: Switching from metformin to Glucovance is dominant to maintaining patients on MET monotherapy with poor control. Further long-term clinical studies with economic data collection are required to confirm these results.