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GPs urged to switch diabetes patients from synthetic insulin to cut costs

GPs should consider switching patients with diabetes from synthetic insulin, say the UK authors of a new analysis that estimates the NHS could have saved up to £625m by using human insulin more widely.

NICE guidelines recommend human insulin to be used as first-line therapy in patients with type 2 diabetes, but the authors of the study say synthetic insulin has become increasingly popular, due to successful marketing campaigns and despite it being more expensive and only having ‘modest benefits’ over human insulin.

Researchers analysed open source data from the four UK prescription pricing agencies for the years 2000 to 2009, adjusted costs for inflation and reported costs at 2010 prices.

The study – published in BMJ Open – shows the NHS spent a total of £2,732m on insulin prescriptions. Prescriptions for synthetic insulin accounted for £1,629m – 59% of the total. Human insulin accounted for £1,056m and animal insulin accounted for £47.2m – 39% and 2% respectively.

Synthetic insulin is designed to better mimic the actions of insulin manufactured by the body, but was 47% more expensive than human insulin in the study – costing on average £2.31 per millilitre, compared with £1.57 per millilitre.

Assuming that all patients who were prescribed synthetic insulin could have alternatively been prescribed human insulin, and not taking account of insulin presentation – such as a phial, a pen or pen-fill device – the researchers estimated the total excess cost of synthetic insulin for this 10-year period at £625m.

Human insulin is usually dispensed as a phial, while synthetic insulin is more often administered with a pen device. And when the method of insulin administration was considered, the incremental cost of synthetic insulin was £541m between 2000 and 2009.

Study author Professor Craig Currie from the Department of Primary Care and Public Health at the School of Medicine, Cardiff University said, ‘While it has been shown that insulin analogues are associated with reduced weight gain, less hypoglycaemia (particularly nocturnal), improved lowering of postprandial glucose and improved dosing schedules, most commentators agree that these benefits are modest in comparison to human insulin.’

But, he added that the cost effectiveness of synthetic insulin depended on the type of diabetes, the individual patient and the type of synthetic insulin used.

He said: ‘For example, rapid-acting insulin analogues in patients with type 1 diabetes are likely to be a cost-effective use of finite healthcare resources.’

Dr Brian Karet, a GPSI in diabetes in Bradford, said the benefits of synthetic insulin were ‘marginal’ and so GPs should consider switching patients to human insulin in light of these findings.

He said: ‘I think it is essential that we do this. It will certainly save a significant amount’.

‘Commissioning groups are already considering costs and benefits, and this is a very obvious one.’