LONDON, July 18 (Reuters) Nearly two-thirds of diabetics in Britain do not take their medication as prescribed because they don't fully understand the disease, according to a report today.

One in five of the two million people with diabetes are suffering from preventable complications as a result, it said.

The report is a joint venture between Diabetes UK, the Association of the British Pharmaceutical Industry (ABPI) and independent body Ask About Medicines.

It said the problem was due in part to people not fully understanding the disease, with more than a third saying they did not realise they would have the condition for life.

Many struggled to understand medical terms and were too embarrassed to ask questions.

''Short-termism is a great enemy of good diabetes care,'' said Director of Care and Policy at Diabetes UK, Simon O'Neill.

''Many people struggle to realise the importance of taking their medicines, especially if the consequences are not immediately apparent, despite the fact that damage caused by not taking their medicines is irreparable.'' The report will be presented to the Department of Health today.

It urges those in the health profession to provide more information to patients as well as encouraging them to ask more questions.

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