Diabetes drugs taken by thousands linked to cancer of the pancreas and other serious health problems Man-made version of hormone that helps control blood sugar was approved for use in 2009 25,000 prescriptions of the drugs are issued each year Documents show drug could lead to pancreatitis and pancreatitc cancer Disease has one of lowest cancer survival rates with 5% patients surviving five years beyond diagnosis By Sophie Borland Health Reporter Potentially harmful: An investigation by the British Medical Journal and Channel 4 Dispatches found that manufacturers may be trying to hide the drug's dangerous side effects Diabetes drugs taken by thousands of Britons may contribute to the causes of pancreatic cancer, an investigation will claim today. It has uncovered evidence that an increasingly popular group of injections causes serious health problems. The drugs have been hailed as a revolution in the treatment of type-2 diabetes, which affects 2.5 million Britons. They contain a man-made version of the hormone glucagon-like peptide 1 (GLP-1), which is produced by the intestines and prompts the body to release insulin - the chemical that controls blood sugar levels. The drugs also suppress appetite and can help patients lose weight. Obesity is the main cause of type-2 diabetes and patients can successfully control the illness if they keep their weight down. The GLP-1 drugs were first approved for NHS use by the watchdog NICE in 2009 and around 25,000 prescriptions are issued each year. But it is unclear exactly how many patients are taking them as some get monthly prescriptions while others receive longer or shorter supplies. The drugs are sometimes referred to as Exenatide and Liraglutide, and sold as Byetta and Victoza. But an investigation by the British Medical Journal and Channel 4 Dispatches found that manufacturers may be trying to hide potentially harmful side effects. It uncovered documents showing the drugs increase the risk of pancreatitis, which leads to 1,000 deaths in Britain a year. The investigation also found research which showed a number of patients taking the drugs had developed pancreatic cancer. The disease has one of the lowest survival rates of all cancers, with only 5 per cent of patients living five years beyond diagnosis. Separate research by the University of California, Los Angeles, found that the drugs caused tumours which may lead to cancer in animals. Innovative: The drugs were first approved for the NHS in 2009. They suppress appetite and can help patients lose weight - a key part of controlling the illness Dr Deborah Cohen, the BMJ's investigations editor, said the individual pieces of evidence "may seem inconclusive" on their own, but added: "When considered alongside other emerging and long standing evidence, a worrying picture emerges, posing serious questions about the safety of this class of drug." Dr Fiona Godlee, BMJ editor-in-chief, said the manufacturers had been "unwilling to share their data" and that patients and doctors had "not been kept properly informed about the uncertainties surrounding these drugs." The manufacturers said they were committed to patient safety and insisted they monitor their drugs with rigorous processes. Channel 4"s Dispatches aired last night at 8pm.