The Anglo-Danish-Dutch Study of Intensive Treatment In People with Screen Detected Diabetes in Primary Care (ADDITION study) was initiated in 1999. The primary objectives of the study were:

  • To evaluate whether population-based screening for undiagnosed type 2 diabetes was feasible in a primary care setting
  • To assess whether subsequent optimised intensive treatment of diabetes and associated risk factors among screen-detected patients were feasible in primary care and benefitted the patients, and
  • To quantify the harms associated with screening. Previous screening studies have focused on people with pre-diabetes and how to prevent progression from pre-diabetes to diabetes.



Type 2 diabetes is a common chronic disease. It affected 350 million people worldwide in 2011 and is predicted to reach 550 million by 2030.

A large proportion (up to 50%) of people with diabetes have been shown to remain undiagnosed and untreated. People with diabetes have higher cardiovascular risk. Up to 50% show evidence of micro- or macro-vascular complications at diagnosis. Complications of diabetes are associated with reduced life expectancy and lower quality of life. Intensive treatment of single and multiple risk factors (elevated glucose, lipids and blood pressure) has been shown to reduce the risk of developing vascular complications in people with clinically diagnosed type 2 diabetes.

Diabetes-related expenses were estimated to reach approximately 10% of the total healthcare budgets in 2010 and are expected to increase to 17% in 2035.  


Screening for diabetes has been recommended in several countries, in line with the conclusions from a modelling study. However, direct evidence from randomized controlled trials is still lacking.

Little is known about the magnitude of the benefit of treatment in the lead time between detection by screening and clinical diagnosis and the magnitude of the direct and indirect harms associated with screening. Additionally, more data are needed on the overall cost-effectiveness of screening programmes.