"There are few data about the impact of the recently-defined category of prehypertension (systolic blood pressure 120 to 139 mm Hg or diastolic blood pressure 80 to 89 mm Hg) on cardiovascular disease incidence," Dr. Ying Zhang, of the University of Oklahoma Health Sciences Center, Oklahoma City, and colleagues write. "It is also unknown whether this association differs between individuals with or without diabetes."

The researchers examined the prevalence of prehypertension in 2629 subjects enrolled in the Strong Heart Study, a population with a high prevalence of diabetes. They also assessed hazard ratios for cardiovascular disease with prehypertension in patients with and without diabetes. The participants were free from hypertension and cardiovascular disease at baseline and were followed for 12 years for incident cardiovascular disease. Approximately 42% had diabetes.

Patients with diabetes had a higher prevalence of prehypertension than did those without diabetes (59.4% versus 48.2%, p < 0.001).

There were a total of 389 incident cardiovascular disease events during follow-up. Diabetic subjects with prehypertension had the highest cumulative incidence of cardiovascular disease during follow-up. The lowest cumulative incidence was found in nondiabetic patients with normal blood pressure.

Compared with nondiabetic normotensive subjects, the hazard ratio of cardiovascular disease for those with diabetes and prehypertension was 3.70. For those with diabetes alone or with prehypertension alone, the hazard ratios were 2.90 and 1.80, respectively. The risk of cardiovascular disease in prehypertensive subjects was greatly increased with impaired fasting glucose and impaired glucose tolerance.