Previews of the film, The Edge of Love, an account of Dylan Thomas's life that opens in London on June 20 and nationwide on June 27. Thomas died in 1953 at the age of 39 while on a lecture tour in New York. Although he didn't survive long enough to have been affected by the end of rationing in Britain, a quick glance at photographs show that he was hardly under-nourished. But ill-health plagued his later years and he died early.

Dylan Thomas had been overweight since childhood. One look at his beer belly and chubby face gave him a misleadingly cherubic appearance. Biographers have described his school days as being characterised by the stereotypical image of the fat boy in class wriggling to get out of games.

It is easy to understand why experts now think that his mystery ill-health had its origins in undiagnosed type 2 diabetes. Thomas not only ate more than he needed to, and from adolescence onwards drank too much, but he also did little exercise.

In the end, he collapsed into a coma, thought to have been brought on by a deadly mixture of alcohol, hard drugs and untreated diabetes. Surprisingly, although diabetes had never been confirmed, it had been suspected and, in that respect, Thomas was one step ahead of the half million people in this country who have the condition but are unaware of it.

By coincidence, the release of the film of Thomas's life comes just after Diabetes Week. The Health Minister Ben Bradshaw is opening the bidding to local authorities for £30 million worth of grants over the next three years that will help to fight obesity and encourage people to take more exercise. It is hoped that this should help to reduce the incidence of type 2.

Type 1 diabetes is a form of diabetes with a rapid onset. It affects the thin as well as the fat, the active as well as the inactive and it usually attacks younger people. Type 1 always needs insulin treatment and those who develop it are known to have a genetic tendency to auto immune diseases.

Type 2 tends to come on rather later in life, although it is sometimes found in adolescents and even children. Lifestyle is an important factor and, although there is a familial link, exercise, diet, stress and obesity are of prime significance.

Dylan's notoriety for avoiding physicial activities at school was perpetuated by his slothful, bohemian unstructured life as an adult. By his own accounts his drinking was excessive. He once claimed to have drunk 18 whiskies at a sitting, though he was known to have been a beer drinker principally: as a famous raconteur, he often exaggerated to hold his audience. Similarly, stories about his life suggest that the only exercise that he took was in bed.

By 2025 there will be 4.2 million people in England with diabetes who will be at risk of developing coronary arterial disease, strokes, peripheral arterial disease - responsible for conditions such as gangrene in the feet and impotence - kidney damage and blindness. Other patients with long-standing diabetes develop neurological symptoms.

The majority of the consequences of diabetes arise from too little exercise and too much food, coupled with poor healthcare. The priority is to make the diagnosis and then to persuade the patient to take appropriate treatment.

Insulin is needed for all type 1 sufferers and for some of those with type 2. Patients with type 2 will not only usually require changes of exercise and dietary habits but an oral hypoglycaemic agent and a statin. Patients with both types of diabetes should be routinely treated with statins, regardless of their cholesterol levels and blood pressure. Their blood sugar should be kept at a lower level than would be considered necessary in those without diabetes. Many patients with diabetes will also need treatment for blood pressure and to reduce the likelihood of kidney damage. However well diabetes is controlled, too frequently sufferers still develop coronary arterial disease. Fortunately a glitazone, called Actos pioglitazone, seems to treat those parts of the coronary arteries that other treatments do not.

Actos has been shown to influence the rate at which plaques form in the coronary arteries. It also makes those that are already there more stable and less likely to rupture, and thereby reduces the chance of a coronary thrombosis.