HbA1c overtesting and overtreatment in the US: Might it also be happening in the UK?

The fascinating paper by McCoy et al (summarised alongside) sheds a lot of light on HbA_1c overtesting and overtreatment in the US. The study was a retrospective data analysis of 31545 people with type 2 diabetes from a national administrative database. The participants were aged 18 years and over, had type 2 diabetes with stable glycaemic control (two consecutive HbA_1c measurements <53 mmol/mol [7.0%] within a 2-year period), did not use insulin, had no history of severe hypoglycaemia or hyperglycaemia and were not pregnant. HbA_1c test frequency was assessed within 24 months of the second index HbA_1c test. The frequency of HbA_1c testing was classified as recommended (once or twice per year), frequent (three or four times per year) or excessive (five or more times per year). Changes in treatment regimen were ascertained within 3 months of the index test.

The mean age of the cohort was 58 years and the mean index HbA_1c was 44 mmol/mol (6.2%). Testing frequency was defined as frequent in 55% of participants and excessive in 6%. Despite good glycaemic control at baseline, treatment was further intensified by addition of glucose-lowering agents or insulin in 7% of those tested as per guidelines, 9% of those tested frequently and 13% of those tested excessively.

The authors conclude that in this US cohort of adults with stable and well-controlled type 2 diabetes, 60% received too many HbA_1c tests, a practice associated with potential overtreatment with hypoglycaemic drugs. Excessive testing contributes to the growing problem of waste in healthcare and increased patient burden in diabetes management.

Could this overtesting and potential overtreatment be happening in England and Wales? The most recent National Diabetes Audit (NDA) report for England and Wales shows that, among the 8198 participating practices, 94.8% of people with a diagnosis of type 2 diabetes in their GP records had at least one HbA_1c measurement in the previous 12 months (Health and Social Care Information Centre, 2016). Such results are usually interpreted as “5.2% have not had an HbA_1c measurement. How scandalous.” The idea that the 94.8% figure might include people who have had too many HbA_1c measurements has not, in my opinion, really been considered or measured.

The NDA report also shows that 66.1% of people with type 2 diabetes in the audit achieve an HbA_1c of ≤58 mmol/mol (7.5%). Again, this result is usually interpreted as “32.9% fail to achieve good control. How scandalous.” However, we know that some older frail people with diabetes, especially nursing home residents, are being overtreated, putting them at increased risk of hypoglycaemia (Gadsby et al, 2012). In addition, might the NDA’s 66.1% also include some people who are not old and frail, whose HbA_1c levels are inappropriately low and who might benefit from a reduction in their glucose-lowering medications?

To read the article summaries, please download the PDF