AIMS/HYPOTHESIS: Trials have not demonstrated benefits to the population of screening for type 2 diabetes. However, there may be cost savings for those found to have diabetes. We therefore aimed to compare healthcare costs among individuals with incident type 2 diabetes in a screened group with those in an unscreened group. METHODS: In this register-based, non-randomised controlled trial, eligible individuals were men and women aged 40-69 years without known diabetes who were registered with a general practice in Denmark (n = 1,912,392). Between 2001 and 2006, 153,107 individuals registered with 181 practices participating in the Anglo-Danish-Dutch Study of Intensive Treatment in People with Screen Detected Diabetes in Primary Care (ADDITION)-Denmark study were sent a diabetes risk-score questionnaire. Individuals with a moderate-to-high risk were invited to visit their family doctor for assessment of diabetes status and cardiovascular risk (screening group). The 1,759,285 individuals registered with all other practices in Denmark constituted the retrospectively constructed no-screening (control) group. In this post hoc analysis, we identified individuals from the screening and no-screening groups who were diagnosed with diabetes between 2001 and 2009 (n = 139,075). Using national registry data, we quantified the cost of healthcare services in these two groups between 2001 and 2012. From a healthcare sector perspective, we estimated the potential healthcare cost savings for individuals with diabetes that were attributable to the screening programme. RESULTS: In the screening group, 27,177 of 153,107 individuals (18% of those sent a risk-score questionnaire) attended for screening, 1533 of whom were diagnosed with diabetes. Between 2001 and 2009, 13,992 people were newly diagnosed with diabetes in the screening group (including those diagnosed by screening) and 125,083 in the no-screening group. Healthcare costs were significantly lower in the screening group compared with the no-screening group (difference in mean total annual healthcare costs -€889 per individual with incident diabetes; 95% CI -€1196, -€581). The screening programme was associated with a cost saving per person with incident diabetes over a 5-year period of €2688 (95% CI €1421, €3995). CONCLUSIONS/INTERPRETATION: Healthcare costs were lower among individuals with incident type 2 diabetes in the screened group compared with the unscreened group. The relatively modest cost of screening per person discovered to have developed diabetes was offset within 2 years by savings in the healthcare system.