(HealthDay News) — After a heart attack, the risk of developing diabetes and so-called pre-diabetes rises steeply, a new study finds.

In fact, recent heart attack patients are up to four-and-a-half times more likely to develop diabetes compared with the general population and more than 15 times more likely to develop high blood sugar, according to the report in the Aug. 25 issue of The Lancet.

"Having a heart attack means that the chances of getting diabetes later are increased," said Dr. Lionel Opie, director of the Hatter Cardiovascular Research Institute at the University of Cape Town, South Africa, and author of an accompanying journal editorial. "We already know that diabetes predisposes one to heart attack, now we add that heart attacks predispose one to diabetes -- one nasty disease leads to another, and it's a two-way process."

In the study, a team led by Dr. Roberto Marchioli, from the Laboratory of Clinical Epidemiology of Cardiovascular Disease, Consorzio Mario Negri Sud, Chieti, Italy, collected data on almost 8,300 Italian patients who had suffered a recent heart attack and were not previously diabetic.

More than three and a half years after the heart attack, a third of the patients had developed diabetes or had impaired insulin resistance (a precursor to diabetes), as measured by an increase in blood sugar.

When they used a lower threshold for measuring blood sugar, 62 percent of the patients were defined as diabetic.

"These findings further tie the knot between heart attacks and high blood glucose -- each is a risk for the other, the patient thus potentially being caught in a fatal vicious circle," Opie said.

Risk markers for diabetes or high blood sugar include age, high blood pressure, and use of heart medicines such as beta-blockers, cholesterol-lowering drugs, and diuretics.

The researchers found being overweight increased the risk of diabetes. Smoking also increased the risk by 60 percent. In addition, an unhealthy diet and heavy drinking increased the risk of developing diabetes after a heart attack.

"Lifestyle factors can be particularly important in preventing disease," Marchioli said. "The reductions in risk associated with a Mediterranean-type diet suggest that diet could help reduce incidence of pre-diabetes and diabetes after a [heart attack]," he added.

Opie agreed that changing diet and exercising can help cut post-heart attack diabetes risk.

"Once you have had a heart attack, watch for new diabetes --monitor blood sugar and keep exercising a lot," Opie advised. "This 'eats up' the blood sugar. And eat Mediterranean-style, adding olive oil and nuts -- the Mediterranean diet gives some, but not total, protection from new diabetes after a heart attack."

More information

For more on diabetes, visit the American Diabetes Association.

SOURCES: Roberto Marchioli, M.D., Laboratory of Clinical Epidemiology of Cardiovascular Disease, department of clinical pharmacology and epidemiology, Consorzio Mario Negri Sud, Chieti, Italy; Lionel Opie, M.D., director, Hatter Cardiovascular Research Institute, University of Cape Town, South Africa; Aug. 25, 2007, The Lancet