When a man develops type 2 diabetes could determine his risk of a heart attack, a new study finds. In fact, men who have had type 2 diabetes for a decade or more face the same risk as those who have already had a prior heart attack, the researchers found.
The findings, appearing in the Archives of Internal Medicine, may help to stratify patients based on risk level, to better determine who needs what type of care and when.
"You don't want to give all these big, powerful, expensive medicines to every single person. Maybe we can tease out the group that would benefit more," said Dr Robert Scott III, an associate professor of internal medicine at Texas A&M Health Science Center College of Medicine and senior staff cardiologist at Scott & White in Temple, Texas. He was not involved in the new study.
Prior research had indicated that the risk of heart disease in people with type 2 diabetes was the same as in people who had had a previous heart attack. But this research indicates that the risk really does have more to do with timing.
Heart disease and diabetes in men
After following about 4,000 men aged 60 to 79 for nine years, British researchers led by S. Goya Wannamethee of University College London, found a higher risk of heart attacks and death in all those who had diabetes, compared to men who didn't have the illness.
Risk rose along with duration of disease - compared to men without diabetes, men who had early-onset diabetes (in this case, for an average of 17 years or more) had 2.5 times the risk of a heart attack. That level of risk was equal to that of men with a prior history of heart attack, the team noted.
Men who had late-onset diabetes (an average of five years with the disease) had a 54% increased risk of a heart attack or of dying.
The risk for cardiovascular problems rose significantly after a man had had diabetes for eight years, the team found.
None of these risk differences were affected by more typical risk factors for heart attack, such as inflammation of the arteries.
"The bottom line was that men who had had diabetes longer, in other words early-onset diabetes diagnosed [in this study] before age 60, had more heart attacks and more events," Scott said. "And therefore they truly did look equivalent to patients who had had a prior heart attack and no diabetes. It looks like it really was an equivalent," he added.
Heart risks in women not so great
"If a male aged 60 walks into my office who just got diagnosed yesterday and didn't have any known heart disease, I might not be as aggressive [in treating him] as we are today," he noted. "That way the patient has less side effects to the medicine and less cost."
But another expert said that clinical implications from the new study remain unclear.
Dr Chad Teeters, assistant professor of clinical medicine at the University of Rochester Medical Center, said that one problem with the study was that the patients were all older, many had heart risk factors known as "metabolic syndrome," and many were physically inactive, all of which are risk factors for heart disease.
Given this limitation, he said, the new research "doesn't change the game" of how patients are treated.
The study didn't look at men under the age of 60, but the authors did note that people are now getting diagnosed with type 2 diabetes at earlier and earlier ages, perhaps indicating more people who are in need of more aggressive treatment.
And what about the heart risks posed to women by diabetes?
According to Teeters, "Cardiac risk in women doesn't begin to accumulate until later in life due to the protective effects of oestrogen, so the effect of duration of diabetes may or may not be similarly associated with cardiac risk in women as it is in men."
Another expert agreed.
"Studies have shown that diabetes is more of a risk factor for heart attacks in men, [but] we don't know anything about [women's risk] from this study," noted Dr. Suzanne Steinbaum, a preventive cardiologist with Lenox Hill Hospital in New York City. "I don't think this gives us any information on women."
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