On the use of ambulatory blood pressure recordings and insulin sensitivity measurements in support of the insulin-hypertension hypothesis

OBJECTIVE: To determine the possible correlations between ambulatory blood pressure and insulin sensitivity, compared with correlations between office blood pressure and insulin. DESIGN: Observational study. SETTING: Policlinic at the Department of Geriatrics, Uppsala, Sweden. PATIENTS: Caucasian patients (n = 149) of both sexes with untreated essential hypertension. MAIN OUTCOME MEASURES: The hyperinsulinaemic euglycaemic clamp and office blood pressure in all subjects. In subgroups, also the oral glucose-tolerance test (n = 96) and 24-h ambulatory blood pressure (n = 84). RESULTS: Significant correlations were seen between the insulin sensitivity index and ambulatory blood pressure recordings, whereas fasting plasma insulin levels were uncorrelated with office blood pressure. The insulin sum and the 2-h insulin level of the oral glucose-tolerance test were more closely correlated with ambulatory blood pressure recordings than was the fasting insulin level. In multiple regression analyses the night-time diastolic blood pressure showed a significant correlation with the insulin sensitivity index even after controlling for the effects of sex, age and body mass index. CONCLUSION: The apparent association between blood pressure and insulin resistance not only is obscured by measurement error, but is also affected by the particular measures of insulin resistance and blood pressure used. The present study provides further evidence that a relationship exists between blood pressure and hyperinsulinaemia or insulin resistance.