Adiponectin, insulin resistance, and left ventricular structure in dipper and nondipper essential hypertensive patients

Background Adiponectin is an adipocyte-derived protein with insulin-sensitizing and antiatherogenic properties. Failure to decrease blood pressure (BP) normally during night in hypertensive patients has been independently associated with left ventricular hypertrophy. Methods We examined the relationship between adiponectin levels, insulin sensitivity, and left ventricular structure in 40 newly diagnosed never-treated patients with essential hypertension, including 20 patients with a normal night-time pressure decrease (ie, dippers) and 20 patients with BP persistently elevated throughout the 24-h period (ie, nondippers). All subjects had grade 1–2 hypertension, aged 18 to 65 years, no diabetes mellitus, no obesity, no hyperlipidemia, and no cardiopulmonary, renal, or hepatic disease. Results The two groups of patients were similar for age, sex, body mass index, and had no differences for clinic, 24-h, and diurnal BP, and 24-h, diurnal, and nocturnal heart rate, as well as glucose, total cholesterol, and triglyceride levels. Plasma insulin and homeostasis model assessment (HOMA index) were higher (P< .01), and adiponectin levels were lower (P< .005) in nondippers than in dippers. Adiponectin correlated inversely with HOMA index and insulin levels (r = −0.58, and r = −0.62, respectively, P< .001) in the entire population. Nondippers showed left ventricular mass, relative wall thickness, and measure of early and late diastolic peak flow velocity ratio similar to those of dippers. Conclusions In the absence of major cardiovascular risk factors, nondipper essential hypertensive patients show more prominent insulin resistance and lower adiponectin compared to dippers. Therapeutic modulation of adiponectin or insulin resistance might provide additional benefit to the conventional antihypertensive treatment.