Impaired glucose tolerance, a precursor to full-blown diabetes, is associated with an increased risk of stroke in non-diabetic patients who have already experienced a minor or mini-stroke, Dutch researchers report.

Symptoms of a mini-stroke, known medically as a transient ischemic attack (TIA), are exactly the same as those of a full-fledged stroke, but resolve within 24 hours. While TIAs in themselves cause no long-term problems, they substantially increase the likelihood of having a full-fledged stroke soon afterwards.

Impaired glucose tolerance has been linked to stroke in patients with coronary artery disease. However, it was unclear if this metabolic derangement increased the risk in patients with a prior TIA or minor stroke.

Dr. Sarah E. Vermeer, from the Erasmus Medical Center in Rotterdam, and colleagues assessed the impact of glucose tolerance on stroke risk in 3,127 patients with a prior TIA or minor stroke.

During an average of 2.6 follow-up, 272 patients developed a stroke and 200 patients experienced heart attack or cardiac death.

An 80 percent increased stroke risk was seen in patients with impaired glucose tolerance. Patients with excessively low glucose levels also had a 50 percent greater risk than did those with normal glucose levels.

The biggest risk of stroke - a nearly threefold increased risk compared with normal glucose levels - was in patients with overt diabetes.

By contrast, the glucose levels seemed to have no bearing on the risk of heart attack or heart-related death, the report indicates.

“Intensive glucose control in both type 1 and type 2 diabetic patients seems to reduce stroke and other macrovascular events,” the authors state. “New secondary prevention trials should be initiated to investigate whether intensive glucose control reduces stroke incidence in these patients.”

SOURCE: Stroke June 2006.