The number of adults worldwide with diabetes has more than doubled in three decades, jumping to an estimated 347 million, a new study says. Much of that increase is due to ageing populations  since diabetes typically hits in middle age  and population growth, but part of it has also been fuelled by rising obesity rates. With numbers climbing almost everywhere, experts said the disease is no longer limited to rich countries and is now a global problem. Countries in which the numbers rose fastest include Cape Verde, Samoa, Saudi Arabia, Papua New Guinea and the United States. \"Diabetes may well become the defining issue of global health for the next decade,\" said Majid Ezzati, chair of global environmental health at Imperial College London, one of the study authors. He noted the figures do not reflect the generations of overweight children and young adults who have yet to reach middle age. That could create a massive burden on health systems. \"We are not at the peak of this wave yet,\" he said. \"And unlike high blood pressure and cholesterol, we still don\'t have great treatments for diabetes.\" Experts weren\'t sure why and said there could be several reasons, including worse detection of the disease, genetic differences, or perhaps the Europeans were better at getting heavy people to reduce their chances of developing diabetes. Ezzati and colleagues examined more than 150 national health surveys and studies that tracked Type 2 diabetes in adults older than 25 in 199 countries and territories.