Education And Debate

Should we screen for type 2 diabetes? Evaluation against National Screening Committee criteria

BMJ 2001; 322 doi: http://dx.doi.org/10.1136/bmj.322.7292.986 (Published 21 April 2001) Cite this as: BMJ 2001;322:986
  1. Nicholas J Wareham (njw1004@medschl.cam.ac.uk), clinical scientist,
  2. Simon J Griffin, lecturer
  1. Department of Public Health and Primary Care, Institute of Public Health, University of Cambridge, Cambridge CB2 2SR
  1. Correspondence to: N Wareham
  • Accepted 20 October 2000

The high prevalence of undiagnosed diabetes1 and the proportion of cases with evidence of complications at diagnosis 2 3 undoubtedly create a strong imperative for screening. In the United Kingdom, the National Screening Committee has the task of providing advice about established and newly proposed screening programmes and aims to evaluate these against specified criteria.4 This article evaluates screening for type 2 diabetes in relation to these criteria.

Summary points

Benefits of early detection and treatment of undiagnosed diabetes have not been proved

Effectiveness of diabetes screening in reducing cardiovascular disease depends on disease prevalence, background cardiovascular risk, and risk reduction in those screened and treated

Disadvantages of screening are important and should be quantified

Universal screening is unmerited, but targeted screening in specific subgroups may be justified

Clinical management of people with established diabetes should be optimised before a screening programme is considered

The condition

The first group of issues considered by the National Screening Committee relates to the condition for which screening is proposed. In the case of type 2 diabetes, these issues are relatively uncontroversial. The scale of morbidity and mortality attributable to diabetes is not in question,5 and the longitudinal examination of cohorts has established the overall course of the condition.6 Undiagnosed diabetes is common7; it is not generally characterised by recognised symptoms and is as strongly associated with future risk as diagnosed diabetes.8 Up to 25% of people with diabetes have evidence of microvascular complications at diagnosis, 1 3 and extrapolation of the association between the prevalence of retinopathy and the duration of disease suggests that the true onset of diabetes occurs several years before it is recognised clinically.2 The National Screening Committee's criteria also state that all “cost-effective primary prevention interventions should have been implemented as far as practicable.”4 …

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