Poor glucose metabolism risks clots.

Insulin builds up in the blood when cells fail to respond to the hormone's signal to take up glucose--as occurs in type II, or adult-onset, diabetes. Scientists have known for decades that people with such insulin resistance face an increased risk of heart disease (SN: 5/25/96, p. 324). It goes beyond the dangers attributable to factors such as high blood pressure or elevated cholesterol. Researchers now report that the insulin buildup may prevent these people from breaking down blood clots efficiently and so contribute to increased heart-attack risk.

James B. Meigs, a physician and epidemiologist at Massachusetts General Hospital and Harvard Medical School, both in Boston, and his colleagues studied 2,962 seemingly healthy people, average age 53. The researchers had participants fast overnight and then tested their metabolism of glucose. The scientists found that 80 percent of the volunteers processed this simple sugar normally; 15 percent were glucose intolerant, a condition that often precedes type II diabetes; and 5 percent had diabetes but didn't know it.

High blood concentrations of insulin, which were most likely to show up in people with diabetes and glucose intolerance, coincided with elevated concentrations of a substance that inhibits one of the body's best clot-busting agents, the team reports in the Jan. 12 JOURNAL OF THE AMERICAN MEDICAL ASSOCIATION.

"Our data strongly suggest that insulin resistance is linked to arterial clotting," says Meigs. It's still unclear whether physicians could determine patients' risk of heart disease by measuring insulin or other substances that influence clotting, he says. "It's something we and others are working on."