Treat all diabetics like heart attack survivors?
Should diabetics be treated as though they have already had a myocardial infarction (MI)? Risk factors for coronary heart disease are so high for Type II diabetic patients that a recent study in Finland concludes that the risk for diabetics with no previous MI is as high as for non-diabetics who have already had an MI.
Steven M. Haffner, MD, professor of medicine at the University of Texas Medical School in San Antonio and lead author of the study, says, "Implicitly, you have to believe that glycemic control intervention alone is not going to eliminate the excess risk."
The seven-year study published in the New England Journal of Medicine followed 1,373 non-diabetic subjects and 1,059 diabetics, all of them Finns.
Among the group, MIs were experienced with the following distribution:
- Non-diabetics with prior MI 18.8%
- Non-diabetics without prior MI 3.5%
- Diabetics with prior MI 45.0%
- Diabetics without prior MI 20.2%
The study is intended, at least in part, to address the controversy about how aggressively to treat cardiovascular risk factors in diabetics, including the suggestion that diabetics should be treated as though they already have coronary heart disease.
Subjects for the study were chosen from Finland’s government register of patients who receive reimbursement for drugs. Researchers chose subjects between the ages of 45 and 64 born and living in eastern and western Finland. Residents of western Finland have a significantly lower rate of heart disease than those living in the east. "People in Finland have higher levels of coronary heart disease and low-density lipoprotein (LDL) than Americans," Haffner says. "But within Finland, there are variations, and if you take those lower-risk areas, they are not very dissimilar to American data."
Between 1982 and 1984, patients were interviewed at the outset and asked about smoking, alcohol intake, drug use, physical activity, and any history of chest pain suggestive of coronary heart disease. Blood pressure, blood glucose, lipids, and lipoproteins were measured.
Two investigators reviewed medical records, and following World Health Organization (WHO) guidelines regarding chest pain symptoms, electrocardiographic changes, and enzyme determinations defined previous MIs. WHO criteria to determine previous strokes were also followed.
In 1990, surviving patients were questioned about hospitalization for acute chest pain and symptoms suggestive of stroke. Death records were also scrutinized. The results show:
• In both diabetic and non-diabetic subjects, a history of MI at the baseline was significantly associated with increased incidence of MI (fatal and non-fatal), stroke (fatal and non-fatal), and death from cardiovascular causes.
• Diabetics with prior MI had the worse prognosis, while non-diabetics without prior MI had the best prognosis.
Since previous studies show diabetic men have a higher risk for death from a first MI than women, Haffner advocates aggressive treatment for men very early after diagnosis, in view that the average age of diagnosis is 51. "If they are diagnosed in their 40s or 50s, then that should kick in immediately because they are already at high risk of death by then," he says. "But if somebody develops diabetes at 25, while their lifetime risk is much higher, their immediate risk isn’t all that high, so you might delay a couple of years."
Haffner adds that several clinical studies of these issues are currently under way and some results are expected in 1999. While he "doesn’t expect definitive results that soon," over the next three or four years, much more clinical information will be available.
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