More than 650,000 people with obesity-related diabetes are risking serious health problems such as stroke and blindness because they do not take their medicines, a charity says today.

Type 2 diabetes, which is rapidly on the rise as the adult population gains weight, can lead to a range of complications, such as heart disease, kidney problems and amputations, unless it is kept under control. Some 2 million people suffer from type 2 diabetes but the charity Diabetes UK says 650,000 of them are not taking their medication as they should.

"Many people struggle to realise the importance of taking their medicines despite the fact that damage caused is irreparable," said Douglas Smallwood, Diabetes UK's chief executive. "Effectively controlling type 2 diabetes can reduce the risk of heart disease by 56%, and eye disease and kidney disease by 33%."

Research by the charity, together with the Association of the British Pharmaceutical Industry, found that one in five people with diabetes did not think it important to take their prescription. It found that 40% of sufferers did not realise they could be in danger of having a stroke if their diabetes was not properly managed, 32% did not know heart disease was a common complication and 30% did not know failing to take the tablets could put them at risk of kidney failure.

People with type 2 diabetes may need to take several glucose-lowering tablets, blood pressure tablets, and lipid-lowering agents. Because complications can take years to develop, sufferers may not appreciate the risks of not taking the drugs.

"Diabetes UK is currently working with healthcare professionals to encourage people with diabetes to be more involved in their healthcare," said Smallwood.