Eli Lilly, a corporate sponsor of Diabetes UK, has been censured by the Medicines and Healthcare products Regulatory Agency for allowing a leaflet that discussed links between mental illness and diabetes to carry only the Diabetes UK logo, and not its own.
The health charity that complained, which did not want to be identified, was concerned that by omitting its own logo the drugs giant had not made clear that it wrote, paid for and distributed the publication Diabetes: Facts To Consider When Caring For Mental Illness.
The regulator said: "We were extremely concerned that the leaflet produced by Eli Lilly purported to be a Diabetes UK publication because of the prominent inclusion of the charity's logo and the absence of any reference to Eli Lilly."
The MHRA was also concerned that the leaflet, aimed at health professionals, did not refer to the current debate about the links between antipsychotic treatments, high glucose levels and diabetes.
Nor had Eli Lilly declared its own interest, said the agency - the company produces Zyprexa, a drug used in the treatment of schizophrenia but which is linked with high glucose levels and, in some cases, diabetes.
The complaint was upheld and Eli Lilly withdrew the leaflet in May last year. It put a statement on the Diabetes UK website two weeks ago, saying it regretted any "misleading impression".
Because this was the first ruling of its kind in the UK, the regulator had to devise internal guidance specifically for it.
The issue highlights the need for better guidance and greater transparency between charities and their drug company sponsors.
"The co-operation between pharmaceutical firms and patient groups is not legislated for," said an MHRA spokeswoman. "If it was Lilly's leaflet, Diabetes UK shouldn't give its label away."
But Diabetes UK, whose ethical policy prevents it from receiving more than 5 per cent of its income from any one company, maintained that the leaflet was wholly written by Lilly and the charity only advised. Dawn Jackson, director of marketing and membership, said it had not known that the drugs giant, which it still works with, had not mentioned its own involvement.
"Our policy makes it clear that if we're working with a corporate partner it will appear on the publication," said Jackson. "In this instance, the logo did not appear.
"We would always ask to see the final copy and have always done so, because our reputation is important to us. We believe we asked, but we have no record of that - and the person who dealt with it left 18 months ago.
"We have spoken with Lilly and been assured this was a one-off."