STOCKHOLM — Type 2 diabetes, by itself, does not boost the risk of cardiovascular events. It's only when type 2 diabetes and coronary artery disease coincide in a patient does diabetes raise the risk, according to findings from 750 patients.
“Type 2 diabetes is not a coronary artery disease (CAD) risk equivalent,” Heinz Drexel, M.D., said while presenting a poster at the annual congress of the European Society of Cardiology. “The prognosis of patients with type 2 diabetes but no coronary artery disease is significantly better than [that of] patients with coronary artery disease but no diabetes,” said Dr. Drexel, director of the Vorarlberg Institute for Vascular Intervention and Treatment in Feldkirch, Austria.
The study reviewed the outcomes of 756 patients who underwent coronary angiography at the institute from October 1999 to October 2000. The analysis excluded six patients with type 1 diabetes. Among the remaining patients, 244 (33%) had no type 2 diabetes or coronary disease, 50 (7%) had type 2 diabetes and no coronary disease, 342 (46%) had coronary disease but no diabetes, and 114 (15%) had both coronary disease and type 2 diabetes. Those with diabetes but no coronary disease had diabetes for an average of 2 years. Those with diabetes and coronary disease had diabetes for an average of 8 years.
During 3.9 years of follow-up, the patients had a total of 151 cardiovascular events, a 20.1% incidence rate.
The event rate was 9% among those who started with no diabetes or coronary disease, 10% among those with diabetes only, 24% among those with coronary disease only, and 40% among patients with both diabetes and coronary disease at baseline. (See box.)
The difference in rates between all of the subgroups was statistically significant, except for those with neither diabetes nor coronary disease and those with diabetes only. The event rate among patients with diabetes only was significantly less than the rate among patients with coronary disease only.
In a multivariate analysis that adjusted for age and gender, patients with diabetes and coronary disease were about five times more likely to have a cardiovascular event than were patients with neither risk factor. Patients with coronary disease only were three times more likely to have an event. But patients with diabetes only were 10% more likely to have an event than those with neither risk factor, a nonsignificant difference.
