The Diabetes UK Annual Conference 2011 heard reports of trusts asking clinicians to predict the exact benefit of IPT in reducing a patient's HbA1c levels before they will fund it.
Speaking at the event in London last week, consultant Dr Peter Hammond said PCTs also ask for IPT to be withdrawn if patients do not show an improvement in HbA1c control.
Yet many of these patients want to continue with the system because it better suits their lifestyle. 'We can try to tie in quality of life, but unfortunately this doesn't cut any ice with PCTs,' he said.
This attitude will be 'quite a significant constraint' on a larger scale roll-out, he added.
NICE recommends continuous subcutaneous insulin infusion, known as an insulin pump, for adults and children over 11 years. They must have either failed to reduce HbA1c levels below 8.5 per cent with multiple daily injections or had disabling hypoglycaemia from such attempts.
IPT technology is gaining traction and more sophisticated equipment launches each year. The latest devices combine IPT with continuous glucose monitoring to form closed loop insulin delivery systems - known as an 'artificial pancreas'.
This has been shown to reduce night-time hypoglycaemia in children and adolescents with type-1 diabetes (Closed-loop insulin systems 'reduce hypoglycaemia' GP, 12 February 2010), and could cut cases of still-births and maternal deaths in pregnant women.
Professor John Pickup of King's College London, said these devices could be available on the NHS in five to 10 years.
But NICE does not recommend IPT for type-2 diabetes because it says there is a lack of evidence of benefit.
Gillian Morrison, a specialist diabetes nurse at the Royal Liverpool University Hospital, said NICE should reconsider. She said: 'For the more cynical among us, it is just a form of rationing'.