A large-scale diabetes screening programme underway in India will overwhelm the health system with false positive results, according to research.

The programme uses simple tests to screen the general population, and those who test positive have to undergo a second test to confirm the diagnosis.

The new study, which used mathematical models to simulate the outcome of screening the whole population, estimates that between 158 million and 306 million people would be referred for confirmatory testing, but only 26-37 million of those would meet the diagnostic criteria for diabetes.

The researchers say the number of tests would be hugely expensive, place a huge burden on the health system, and cause unnecessary worry for patients who don’t require treatment.

Lead author of the study Dr Sanjay Basu, from the Prevention Research Center at Stanford University, said: “The tools we have available are just not good enough to make a programme like this worthwhile. Rather than screening the whole population, it would be more beneficial to rely on symptom-based diagnosis as many other countries do. Health system resources can then be focused on managing those we know have diabetes, whose care at the moment is suboptimal.”

Around 12 per cent of adults in India are thought to have type 2 diabetes, but most cases are undiagnosed. If not managed properly, it can lead to serious complications such as cardiovascular disease, stroke, blindness, limb amputation or kidney failure.

Around 53 million people have already been screened in India, and the government plans to continue expanding the programme. People with a high risk of diabetes are identified either using questionnaire or a glucometer – a small device that measures the glucose level in a drop of blood. To make a definitive diagnosis, these people have to undergo a further, more expensive diagnostic blood test.

Researchers from the US, UK and India compared three survey-based screening methods and glucometer tests and estimated the health system implications of applying each across the whole country. Their findings are published today in PLOS Medicine.

There are 567 million people aged 25 to 65 in India who would be eligible for screening. Depending on the method used for screening, between 126 million and 273 million people would get false positive results. The total cost would be between 169 million and 567 million US dollars.

Dr Christopher Millett, an author of the study from the Public Health Foundation of India and the School of Public Health at Imperial College London said: “A huge number of people will be told they have a high risk of diabetes and have to undergo a second test. This will cause a lot of worry for these people unnecessarily, and will also place an enormous burden on the health system to carry out all these tests.”

Reference: Basu S et al. (2015) The Health System and Population Health Implications of Large-Scale Diabetes Screening in India: A Microsimulation Model of Alternative Approaches. PLoS Med 12(5): e1001827. doi:10.1371/journal.pmed.1001827