Pre-diabetes label 'unhelpful and unnecessary'

Labelling people with moderately high blood sugar as pre-diabetic is a drastically premature measure with no medical value and huge financial and social costs, say researchers from UCL and the Mayo Clinic, Minnesota.

The analysis, published in the BMJ, considered whether a diagnosis of pre-diabetes carried any health benefits such as improved diabetes prevention. The authors showed that treatments to reduce blood sugar only delayed the onset of type 2 diabetes by a few years, and found no evidence of long-term health benefits.

Type 2 diabetes is typically diagnosed with a blood test that measures levels of haemoglobin A1c, which indicates average blood sugar level over the last three months. People with an A1c over 6.5% can be diagnosed with diabetes but the latest guidelines from the American Diabetes Association (ADA) define anyone with an A1c between 5.7% and 6.4% as having pre-diabetes.

If the ADA guidelines were adopted worldwide, a third of the UK adult population and more than half of adults in China would be diagnosed with pre-diabetes. The latest study questions the logic of putting a label on such huge sections of the population, as it could create significant burdens on healthcare systems without conferring any health benefits. Previous research has shown that type 2 diabetes treatments can do more harm than good for people with A1c levels around 6.5%, let alone people below this level.

3.2 million people in the UK are currently diagnosed with type 2 diabetes, but approximately 16 million would fall into the ADA's pre-diabetes category. There is a condition known as impaired glucose tolerance (IGT) that affects around 3.7 million adults in the UK (8%). People with IGT are at high risk of diabetes, but the test is more time-consuming than a simple A1c blood test. There is evidence to suggest that interventions can delay the progression of IGT into diabetes, but the ADA category of pre-diabetes also includes another 12 million people who are at a much lower risk of progressing to diabetes, for whom any benefit from treatment is unknown.

The World Health Organisation (WHO) has stated that "use of 'pre-diabetes' is discouraged to avoid any stigma associated with the word diabetes and the fact that many people do not progress to diabetes as the term implies." Guidance from the UK National Institute for Health and Care Excellence (NICE) broadly aligns with the WHO statement, looking to "move away from describing 'pre-diabetes' as a separate condition". So in the way of official authoritative organisations, ADA is pretty much on its own in using this term. Yet it has caught on heavily in the global scientific literature and because of ethnic differences in A1c levels, it may be an even less valid category in other countries and demographics.

"Pre-diabetes is an artificial category with virtually zero clinical relevance," says lead author John S Yudkin, Emeritus Professor of Medicine at UCL. "There is no proven benefit of giving diabetes treatment drugs to people in this category before they develop diabetes, particularly since many of them would not go on to develop diabetes anyway.