Diabetes screening programme 'too inaccurate to have benefit’, say GP academics
The Government’s flagship scheme to tackle rising rates of diabetes is unlikely to have much impact because the blood glucose tests used to identify people at risk are just too inaccurate, leading GP academics have warned.
The team said that as a result the ‘screen and treat’ approach being taken under the national scheme means large numbers of people will be treated unnecessarily while many others who really are at risk will be missed.
The National Diabetes Prevention Programme is being rolled out across 27 areas of the country this year with further expansion planned from April.
Under the scheme, GPs are to screen millions of people for their diabetes risk so that by 2020 around 100,000 ‘at-risk’ people a year are identified and put through lifestyle change programmes to help cut their risk of goingon to develop diabetes.
GPs are expected to refer patients found to have ‘non-diabetic disglycaemia’ – defined by defined as having an HbA1c of 42– 47 mmol (6.0-6.4%) or fasting plasma glucose of 5.5–6.9 mmol/l – to locally tailored lifestyle intervention programmes, which can include group activities such as cookery or dance classes.
But the researchers, led by Professor Trish Greenhalgh from the University of Oxford, say that their analysis of 49 studies of the screening tests showed that the accuracy of these tests for picking up future diabetes was low – fasting glucose is specific but not sensitive, while HbA1c is neither sensitive nor specific, suggesting large numbers will be unnecessarily treated or falsely reassured depending on the test used.
They also looked at 50 trials of lifestyle intervention programmes and found that those lasting three to six years resulted in around a relative 37% reduction in the risk of developing diabetes - meaning around 151 instead of 239 out of 1,000 people would go on to develop it.
The team said the findings show that the approach will only benefit a small proportion of people at high risk and should be complemented by population-wide approaches.
They concluded: ‘As screening is inaccurate, many people will receives an incorrect diagnosis and be referred on for interventions while others will be falsely reassured and not offered the intervention. These findings suggest that “screen and treat” policies alone are unlikely to have substantial impact on the worsening epidemic of type 2 diabetes.’
Dr Jonathan Valabhji, NHS England Nnational cClinical director for obesity and diabetes said: ’The Healthier You: Diabetes Prevention Programme offers evidence based interventions to delay or prevent onset of Type 2 diabetes in those already identified to be at high risk. As this BMJ paper highlights, such lifestyle interventions have been clearly shown to work. Healthier You is not a screening programme; it empowers people who have already been identified through routine clinical practice to reduce their risk. The NHS is not willing to sit idly by while these individuals progress to Type 2 diabetes.’
The diabetes programme
The NHS Diabetes Prevention Programme was launched last year with plans for GPs to screen millions of people in order to identify those at high risk of type 2 diabetes and refer them for exercise and cookery classes.
NHS England says there are as many as five million people ‘on the cusp’ of diabetes and that its prevention programme has the scope to cut the proportion of those going on to develop full-blown diabetes by as much as 30-60%.
After a year of piloting, the programme got underway in earnest last April, with plans to recruit 20,000 ‘at-risk’ people onto lifestyle change programmes over the coming year. However, emerging results from the pilots revealed challenges with recruitment, with only a fifth of those identified as high risk taking part in the scheme in one area.