ARBs reduce blindness risk from diabetes
By Lilian Anekwe
Angiotensin receptor blockers can reduce the risk of retinopathy in patients with diabetes, a major new trial suggests.
The first large-scale DIRECT study found a ‘strong, positive trend' in favour of prescribing candesartan to reduce the incidence and progression of retinopathy.
GPs said the research could support using ARBs ahead of ACE inhibitors in patients with diabetes.
Treatment with candesartan in normotensive patients with type 1 diabetes with no signs of diabetic retinopathy at baseline brought an 18% reduction in incidence of the condition - defined as a two-step change on the Early Treatment Diabetic Retinopathy Study diagnostic scale.
In patients with type 2 diabetes who had diabetic retinopathy, there was a non-significant 13% reduction in the risk of progression among those who were either normotensive or being treated for hypertension.
And in type 2 patients with relatively early signs of diabetic retinopathy, candesartan increased the probability of regression of retinopathy by 34% compared with placebo.
The QOF says patients with diabetes and with proteinuria or microalbuminuria can be treated with either an ACE inhibitor or an ARB. But GPs often come under pressure from PCTs to prescribe ACE inhibitors – which are nearly four times cheaper than ARBs – to avoid going over their prescribing budgets.
There were nearly two million diabetic patients on GP registers in 2006/7 and it is estimated that 65% will develop diabetic retinopathy within five years of diagnosis.
If all were prescribed an ARB – at a net ingredient cost of £20.77 – prescribing budgets could jump by as much as £27 million.
But Professor Nish Chaturvedi, professor of clinical epidemiology at Imperial College London and a member of the trial steering committee, said the results provided GPs with the evidence they needed to justify prescribing ARBs.
He said: ‘This trial does provide GPs – and prescribing advisors – with evidence that candesartan, in addition to its other benefits, can reduce the incidence of diabetic retinopathy and slow its progression and development. This offsets the future costs of diabetic complications.'
Dr George Kassianos, a GP in Bracknell, Berkshire, said: ‘The bottom line for GPs is that we should be prescribing drugs like candesartan to our patients with type 1 and 2 diabetes to prevent both macrovascular and microvascular complications – whatever the cost.'
Results of the DIRECT trial were presented at the European Association for the Study of Diabetes conference in Rome last week and will be published in The Lancet.Diabetec retinopathy: the main cause of blindness from diabetes Diabetec retinopathy: the main cause of blindness from diabetes