Body weight, 24-hour blood pressure profile and insulin resistance in lean and overweight hypertensives and normotensive controls

Abstract

The aim of the study was to examine the relationship between body weight, circadian blood pressure profile, pulse pressure and insulin resistance. The participants were divided into a lean group with a BMI<26 and the overweight group with a BMI ≥26. Sixty-five overweight and 55 lean subjects (age 50.5±14.4 and 49.9±14.4 y, respectively) were included. Ninety five were hypertensives (SBP ≥140 mm Hg and/or DBP≥90 mm Hg on three office measurements). They were kept off antihypertensive agents for at least 3 weeks before the study and then assigned to 24-hour ambulatory blood pressure monitoring (ABPM) and a 2-hour oral glucose (75g)-tolerance test (OGTT). We determined fasting glucose, insulin, and after glucose ingestion. Insulin resistance was estimated by fasting insulin, fasting insulin/glucose ratio, the areas under the curve (AUC) of insulin and insulin/glucose ratio, the homeostasis model insulin resistance index (Homa's index) and the sum of plasma insulin levels 0,30,60, and 120min after the OGTT (ΣIRI). Overweight subjects presented higher waist: hip ratio (0.897±0.090 vs 0.843±0.075, P<.001), AUCInsulin (78.8±56.3 vs 54.5 ± 38.9μU/ml, P<.01), ΣIRI (269.4±197.3 vs 186.6±135.1μU/ml, P<.01), Homa's index (5.22±3.97 vs 3.06±3.21, P<.05), SBP load (% of 24-hour SBP>140 mm Hg) (62.8 ±24.9 vs 51.0±29.6 %, P<.01), and pulse pressure (64.9±13.3 vs 60.4±13.7 mm Hg, P<.01). Nondippers (n=41) compared with dippers presented higher pulse pressure (70.4 ± 12.8 vs 59.0±12.4 mm Hg, P<.001), waist: hip ratio (0.894 ±0.088 vs 0.860 ±0.086, P<.01), AUCInsulin (82.7±54.3 vs 52.4±39.2μU/ml, P<.01) and Homa's index (5.37±3.72 vs 3.12±3.17, P<.01). Correlations of blood pressure and insulin resistance indexes were no significant. BMI was positively related to AUCInsulin (r=0.358), ΣIRI (r=0.338) and Homa's index (r=0.262), all of them P<.01. In conclusion, these date indicate that among normotensive and hypertensive overweight subjects the prevalence of insulin resistance, SBP load and wide pulse pressure were higher than in lean subjects, and that insulin resistance may have some relationship with nondipper profile.