Blood test has potential to detect undiagnosed inherited diabetes cases

A widely available and cheap blood test has 'great potential' to detect thousands of undiagnosed cases of inherited diabetes, researchers have said.

Rack of sample tubes containing blood for analysis
Rack of sample tubes containing blood for analysis

Measuring levels of CRP, a marker of inflammation more commonly used to detect arthritis, could find undetected cases of maturity onset diabetes of the young (MODY). Researchers said this would be faster and cheaper than existing genetic tests, reducing the delay in diagnosis that increases complication risk.

MODY is caused by inherited mutations in regions of DNA involved in glucose processing. Research suggests around 1% of type 1 diabetics – nearly 3,000 patients – and 4% of early-onset type 2 diabetics may be misdiagnosed, as clinicians are failing to spot MODY as the cause of symptoms. Up to 90% of MODY cases are mistakenly diagnosed as type 1 or type 2 diabetes.

Now, a study has found that low CRP levels can effectively distinguish MODY from other types of diabetes. This is because CRP production is linked to the output of the mutated regions of DNA, acting as a marker.

Speaking at the Diabetes UK Professional Conference 2012 in Glasgow last week, Dr Katharine Owen, consultant physician and University of Oxford academic, said patients were waiting ‘far too long’, often around 10-15 years after diabetes onset, for a MODY diagnosis.

'We know that getting treatment and HbA1c [controlled] right from the start actually affects complication risk many years in the future,’ she said. ‘I'm afraid we as clinicians have a big reluctance to question a diagnostic label that's been applied at onset of diabetes. What this means is that we're missing an awful lot of cases of rare diabetes.’

She said detecting MODY was 'important' if patients are to receive the correct treatment. First-line treatment for the main  MODY type is low dose sulphonylureas, not insulin or metformin as with other diabetes patients. In some types of MODY no treatment can affect HbA1c, meaning patients may be over treated.

Further research has found that adding clinical features to a CRP test increases its ability to spot MODY cases to over 90% accuracy. Dr Owen’s team hope to create a clinical algorithm to screen for MODY at onset of diabetes.

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