Should GPs lower HbA1c targets?

The debate about the benefit of intensive blood glucose treatment has been reignited. Tom Moberly reports.

Dr Karet: 'There is growing evidence that very intensive treatment in people with poorly controlled diabetes isn't a great idea'
Dr Karet: 'There is growing evidence that very intensive treatment in people with poorly controlled diabetes isn't a great idea'

Questions have been asked about the value of intensively treating type-2 diabetes since the publication of two pivotal studies in 2008.

The ACCORD and ADVANCE studies, published in June 2008, suggested that tight glycaemic control in established type-2 diabetes had little benefit and could be harmful.

But a new analysis re-examining data from the ACCORD study suggests that rapid lowering of blood glucose levels does not raise mortality (Diabetes Care 2010; 33: 983-90).

In fact, lower HbA1c levels are associated with a lower risk of mortality. The mortality risk is, instead, raised for patients whose blood glucose levels remain high despite intensive treatment, researchers found.

Dr Martin Hadley-Brown, chairman of the Primary Care Diabetes Society, says there has been 'great speculation' as to whether the drive towards tighter target HbA1c levels is appropriate ever since the ACCORD findings were first published.

Value of aggressive treatment
Questions about the value of aggressive treatment intensified when the lowest QOF HbA1c target was lowered from 7.5 per cent to 7 per cent in April 2009. A BMJ editorial said QOF was incentivising 'an outdated treatment strategy'.

The new analysis has not, however, given the all-clear to intensive treatment.

In particular, it has not clarified why more patients given intensive treatment died in the ACCORD study, says Dr Roger Gadsby, associate clinical professor at Warwick Medical School and a GP in Nuneaton, Warwickshire. Intensive treatment still needs to be carefully considered, he believes.

'The results of this study should not alter our present caution about trying to lower HbA1c well below 7 per cent in people with long-standing diabetes using agents that may cause hypoglycaemia.'

RCGP clinical lead for diabetes Dr Brian Karet believes the new analysis needs to be considered alongside studies suggesting a J-shaped relationship between HbA1c levels and mortality.

For instance, in February, a UK team showed that both low and high mean HbA1c values were associated with increased mortality and cardiac events (Lancet 2010; 375: 481-9).

'There is growing evidence that very intensive treatment in people with poorly controlled diabetes isn't a great idea,' he says. 'In some patients it is very difficult to achieve tight control, particularly in many older patients who may have multiple comorbidities. But you need to use some common sense.'

Dr Graham Kramer, a GP in Angus, Scotland, believes the new analysis should not detract from the importance of tackling glucose control in patients with very high HbA1c levels.

'These are the ones who are going to benefit most in terms of risk reduction if they can get their blood less sugary,' he says.

Across-the-board targets
GPs should avoid pursuing across-the-board targets of glycaemic control in their practice diabetes population, he argues.

'The stakeholders who set QOF domains need to be mindful of this and apply pragmatic targets of glycaemic control, in terms of both HbA1c value and percentages of patients achieving that,' Dr Kramer adds.

Following guidelines
Dr Hadley-Brown agrees that it is important to treat each patient as an individual, rather than doggedly following guidelines.

'There is clearly more to be learned on this topic, but over-enthusiastic or uncritical chasing of universal targets, such as QOF, might have unwanted consequences and the decision-makers behind the targets need to consider this very seriously.'

He adds: 'Until we have a clear answer to this debate, we should remember that there is incontrovertible evidence that lower HbA1c levels are associated with fewer diabetes complications.'

Everyone with diabetes has individual circumstances which should guide therapy choices, Dr Hadley-Brown says. 'Good doctors may treat their patients intensively but not aggressively or clumsily.'

HbA1c Timeline

June 2008: ACCORD and ADVANCE studies show tight glycaemic control has little benefit and may be harmful (NEJM 2008; 358: 2545-59 and 2560-72).

March 2009: BMJ editorial warns that new QOF targets risk harming patients (BMJ 2009; 338: b800).

April 2009: Lowest QOF target reduced to 7 per cent.

March 2010: Dutch study suggests there is no basis for HbA1c targets below 6.5 per cent (Br J Gen Prac 2010; 60: 172-5).

April 2010: New ACCORD analysis shows aggressive HbA1c lowering is not behind high mortality in intensively treated patients (Diabetes Care 2010; 33: 983-90).

 

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