Oct. 11 (HealthDay News) -- Compared to women with optimal blood pressure, those with high blood pressure are up to three times more likely to develop type 2 diabetes, a U.S. study finds.

The link between high blood pressure and diabetes risk was independent of factors known to increase the odds of getting diabetes and cardiovascular disease, said the researchers from Brigham and Women's Hospital, Harvard Medical School and the Harvard School of Public Health.

Reporting in the Oct. 9 European Heart Journal, the team tracked the health of more than 38,000 female health professionals for more than 10 years. At the start of the study, the women (all free of diabetes or cardiovascular disease) were divided into four groups based on their blood pressure: optimal -- below 120 mm/Hg systolic, 75 mm/Hg diastolic; normal -- 120-129 mm/Hg systolic, 75-84 mm/Hg diastolic; high-normal -- 130-139 mm/Hg systolic, 85-89 mm/Hg diastolic; and high blood pressure -- at least 140 mm/Hg systolic, 90 mm/Hg diastolic, and/or a self-reported history of hypertension or treatment for the condition.

After 10 years, 9.4 percent of the women in the high blood pressure group had developed type 2 diabetes, compared with 5.7 percent in the high-normal group, 2.9 percent in the normal group, and 1.4 percent in the optimal group.

After adjusting for a number of factors such as age, smoking, alcohol consumption, body mass index, exercise, and family history of diabetes, the researchers concluded that the women with high blood pressure still had a threefold increased risk of diabetes compared to women with optimal blood pressure.

"We found that obesity was also a strong and independent risk factor for the development of type 2 diabetes. However, statistical analyses showed that the relationship between blood pressure and the onset of type 2 diabetes was similar among women who were normal weight, overweight or obese. There was a threefold increased risk from the lowest to the highest BP category within all three weight categories. This analysis showed that the association between blood pressure and diabetes was not explained by weight alone," lead author Dr. David Conen, a cardiologist and research fellow, said in a prepared statement.

Conen and his colleagues suggested that a possible mechanism for the link between blood pressure and diabetes may be endothelial dysfunction -- the disruption of normal biochemical processes carried out by the cells that line the inner surfaces of blood vessels.

"It may be a precursor of both hypertension and diabetes," Conen said. "Thus, the progression of endothelial dysfunction may cause worsening of both BP and blood glucose. This is line with the fact that both BP and blood glucose occur together as part of the metabolic syndrome," a combination of health problems that increase the risk of cardiovascular disease and diabetes.

SOURCE: Oxford University Press, news release, Oct. 9, 2007