Coeliac patients cannot eat many wheat-based products
Campaigners say it reinforces the need for cases to be spotted early, claiming many doctors miss the vital signs until the disease is well-advanced.
Eating certain foods which contain gluten - like wheat - damages the gut lining of a coeliac patient, reducing the ability of the person to absorb vital nutrients from all food.
The research was published in the latest issue of the medical journal The Lancet.
In normal circumstances, fewer than 26 of them would have died - but 53 of the coeliac patients died.
The main cause of death was non-Hodgkin lymphoma - a cancer which is a well-known complication of long-term coeliac disease sufferers.
More worryingly, long delays between the onset of symptoms and diagnosis by doctors greatly increased the chance of death.
One in 300 affected
A delay in diagnosis of 10 years more than trebled the risk in people with severe disease. And those who did not stick to the restricted diet needed by patients increased their chances of death yet further.
Coeliac disease affects an estimated one in 300 people in the UK, and tends to be diagnosed in adulthood rather than childhood.
Many patients suffering the classic symptoms of fatigue, diarrhoea and wasting are told by GPs they are either suffering from anaemia or irritable bowel syndrome - when one in 10 of them has coeliac disease, research from St Thomas' Hospital in London found.
Dr Jocelyn Fraser is working on a project funded by charity Action Research to help spot coeliac patients early.
She said of the new research: "It echoes the need to diagnose sufferers early, and start them on a strict gluten-free diet so as to reduce the long-term health consequences.
"We have made great progress in the early identification of this condition, especially among GPs, and to avoid the long-term health risks and increased mortality in this group of people."