Methods

With no direct evidence of long term benefit from randomised controlled trials in screened populations, we used Medline and the Cochrane Library to identify randomised controlled trials that included populations with clinical diabetes and reported long term outcomes. We also used a model of clinical non-insulin dependent diabetes to estimate outcomes in the absence of screening. 8 9

Screening for disease

Most current screening guidelines and recommendations use a model of disease screening when they suggest screening for diabetes. Research has focused on establishing the sensitivity and specificity of different tests, and tends to measure the success of a diabetes screening programme in terms of the number of new cases identified.10^–12

One problem with focusing on case detection is that the potential benefit of screening is not similar for all cases. The risk of microvascular complications increases with the plasma glucose concentration and the duration of diabetes, while the risk of macrovascular disease depends on age, sex, genes, and lifestyle, as well as hyperglycaemia. As an increased risk of macrovascular disease may occur in people whose plasma glucose concentration is lower than values found in diabetes, it is difficult to identify a single …