OBJECTIVES: To assess the cost-effectiveness (CE) of switching from NPH insulin ± oral glucose-lowering drugs (OGLDs) to insulin detemir ± OGLDs in people with type 2 diabetes (T2DM) in countries in different economic circumstances based on observational data gathered in routine clinical practice. METHODS: The A1chieve® study assessed safety and outcomes over 24 weeks in 66,726 people with T2DM starting insulin analog therapy. Most people (96%) stated better glycemic control as reason to switching therapy, with 31% also stating hypoglycemia problems as a further reason. The CE analyses included data for people switching to detemir in South Korea (n=90) and in seven Arabian Gulf countries (n=124). Data were collected on clinical effectiveness and adverse events, and health-related quality of life using the EQ-5D questionnaire. CE analyses used the IMS CORE diabetes model with 1 and 30 year time horizons, with South Korea and Saudi Arabia country-specific costs for complications and therapies and background mortality rates. CE was measured by comparing outcomes at study-end with outcomes at pre-study. Incremental cost-effectiveness ratios (ICERs) are expressed as cost per QALY in local currencies, USD and in fractions of local GDP per capita. CE was pre-defined using the WHO definition of <3 times GDP per capita.  RESULTS: 1-year ICERs were: South Korea (KWR 3,236,798; USD 2,980; GDP 0.13), and Saudi Arabia (SAR 27,221; USD 7,258; GDP 0.36). 30-year ICERs were: South Korea (KWR 872,589; USD 803; GDP 0.04), and Saudi Arabia (SAR 6,349; USD 1,693; GDP 0.08). Sensitivity analyses covering cost of self-monitoring, deterioration of glucose control with time, and other time horizons showed the results to be robust. CONCLUSIONS: Switching from NPH±OGLDs to detemir±OGLDs in people with T2DM as performed in the A1chieve® study was found to be cost-effective in both country settings at 1 and 30 year time horizons.