Metabolic characteristics of prehypertension: role of classification criteria and gender

OBJECTIVE: We tested whether men and women in the European Society of Hypertension (ESH) high normal and normal blood pressure (BP) categories, all included in the the Seventh Joint National Committee (JNC 7) prehypertension group, share similar metabolic characteristics and whether they differ from men and women with optimal BP (<120/80 mmHg). METHODS: BP (multiple measurements with a standardized automatic device), insulin sensitivity (euglycaemic clamp), oral glucose tolerance test (OGTT), carotid intima-media-thickness (IMT, echo), family history (questionnaire), physical activity (accelerometer), and anthropometrics (bioimpedance) were evaluated in the 1384 healthy European individuals ranging from 30-60 years participating in the multicentre study Relationship between Insulin Sensitivity and Cardiovascular disease (RISC). RESULTS: BMI and waist-to-hip ratio were higher (both P < 0.05 adjusted for age and recruiting centre) in men and women with high normal (but not normal) BP with respect to optimal BP. Similarly, in women (after adjustment for study centre, age, physical activity, and waist), serum triglycerides and carotid IMT were higher in those with high normal (but not normal) BP; moreover, in this group there was a higher prevalence of glucose-intolerance (21.8 versus 9.7%, P = 0.02) and insulin sensitivity tended to be lower (P = 0.07). Insulin sensitivity and diastolic blood pressure were weakly related variables displaying a nonlinear association with a threshold below the normal BP values and no interaction with family history of hypertension. CONCLUSION: The JNC 7 category prehypertension identifies a dishomogeneous group of individuals whereas the ESH classification, particularly in women, was more accurate in identifying both the predisease and the healthy phenotype. Insulin resistance is not a major characteristic of the condition of prehypertension.