Objectives: To reconsider the aims of screening for
undiagnosed diabetes, and whether screening should be
for other abnormalities of glucose metabolism such as
impaired glucose tolerance (IGT), or the ‘metabolic
syndrome’. Also to update the previous review for the
National Screening Committee (NSC) on screening for
diabetes, including reviewing choice of screening test;
to consider what measures would be taken if IGT and
impaired fasting glucose (IFG) were identified by
screening, and in particular to examine evidence on
treatment to prevent progression to diabetes in these
groups; to examine the cost-effectiveness of screening;
and to consider groups at higher risk at which
screening might be targeted.
Data sources: Electronic databases were searched up
to the end of June 2005.
Review methods: Literature searches and review
concentrated on evidence published since the last
review of screening, both reviews and primary studies.
The review of economic studies included only those
models that covered screening. The new modelling
extended an existing diabetes treatment model by
developing a screening module. The NSC has a set of
criteria, which it applies to new screening proposals.
These criteria cover the condition, the screening test
or tests, treatment and the screening programme.
Screening for diabetes was considered using these
criteria.
Results: Detection of lesser degrees of glucose
intolerance such as IGT is worthwhile, partly because
the risk of cardiovascular disease (CVD) can be
reduced by treatment aimed at reducing cholesterol
level and blood pressure, and partly because some
diabetes can be prevented. Several trials have shown
that both lifestyle measures and pharmacological
treatment can reduce the proportion of people with
IGT who would otherwise develop diabetes. Screening
could be two-stage, starting with the selection of
people at higher risk. The second-stage choice of test
for blood glucose remains a problem, as in the last
review for NSC. The best test is the oral glucose
tolerance test (OGTT), but it is the most expensive, is
inconvenient and has weak reproducibility. Fasting
plasma glucose would miss people with IGT. Glycated
haemoglobin does not require fasting, and may be the
best compromise. It may be that more people would
be tested and diagnosed if the more convenient test
was used, rather than the OGTT. Five economic
studies assessed the costs and short-term outcomes of
using different screening tests. None examined the
long-term impact of different proportions of false
negatives. All considered the costs that would be
incurred and the numbers identified by different tests,
or different cut-offs. Results differed depending on
different assumptions. They did not give a clear guide
as to which test would be the best in any UK screening
programme, but all recognised that the choice of cutoff
would be a compromise between sensitivity and
specificity; there is no perfect test. The modelling
exercise concluded that screening for diabetes appears
to be cost-effective for the 40–70-year age band, more
so for the older age bands, but even in the 40–49-year
age group, the incremental cost-effectiveness ratio for
screening versus no screening is only £10,216 per
quality-adjusted life-year. Screening is more costeffective
for people in the hypertensive and obese
subgroups and the costs of screening are offset in
many groups by lower future treatment costs
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