HTA recommends against screening for type 2 diabetes in the UK

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Following on from our report of the ADDITION trial last week, we can add that the UK Health Technology Assessment programme has updated its recommendation against screening for type 2 diabetes.

Their recommendation to the National Screening Committee contains an analysis of new evidence published between 2009 and January 2012.

Elves everywhere – coniferous, deciduous and mixed woodland alike – will find this information extremely helpful!

Methods

This is an updated health technology assessment (HTA) incorporating reviews of the evidence across a number of clinical questions relating to screening for type 2 diabetes.  These include questions relating to:

  • how effective tests for type 2 diabetes are
  • the use of HbA1c, OGTT and other blood glucose tests in a screening context
  • should screening be universal or selective?
  • the use of such tests in the context of cardiovascular risk profiling
  • modifiable and non-modifiable risk factors for type 2 diabetes
  • prevention of type 2 diabetes.

The HTA authors conducted systematic searches for evidence that was published from January 2009 to January 2012.

They critically reviewed the evidence against the National Screening Committee criteria for recommending a screening test.

Results

There is a potential rationale for screening for type 2 diabetes.  The review found evidence that a substantial number of people have undiagnosed type 2 diabetes.  There is also evidence to suggest that these people could benefit as a result of better detection of the disease.

However, the review also found evidence of a need for improvement in care, with large numbers of diagnosed type 2 diabetics not getting the care they need.

Taking a blood sampleThe HTA concluded that screening for type 2 diabetes fails the following NSC criteria:

  • Criterion 12:  optimisation of existing management of type 2 diabetes. A report by the National Audit Office (NAO) gives details of shortcomings.
  • Criterion 13: evidence of benefit from high-quality randomised controlled trials is lacking.  The Ely and ADDITION trials are reviewed in detail.

The reviewers also considered that Criteria 18 (staffing and facilities) and 19 (consider other options, including prevention) have not been met.

Screening tests may be more effective when used selectively, guided by risk factors such as age, ethnicity and cardiovascular risk profile.  However there remain important issues in how the various tests perform (HbA1c, oral glucose tolerance test or OGTT), in different populations and even between different labs.

There may be a role for opportunistic screening of people attending practices showing one or more risk factors.  There was some evidence that screening may be more cost-effective when it is selective.

Effort should be focused on the prevention of diabetes as well.

Comments

  • You won’t find a better review of the evidence on screening for type 2 diabetes in a UK context.
  • The review addresses many of the consequences of screening, such as how to manage the increased detection of Impaired Glucose Tolerance that would result from large-scale screening.
  • Use of HbA1c lacks sensitivity.  It would yield a lot of false negatives, that is, as a screening test it would miss a lot of people with diabetes.
  • It’s possible that other important evidence could emerge  that will alter the conclusion.  Or, more likely, provide clearer guidance on targeting of diabetes tests.
  • The review covers a very broad scope and it’s not clear exactly what search strategy was implemented for each question. That said, it seems unlikely that a substantial body of evidence has been missed.

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