Nonalcoholic fatty liver disease, adiponectin and insulin resistance in dipper and nondipper essential hypertensive patients

OBJECTIVE: The pathogenesis of nonalcoholic fatty liver disease (NAFLD) is multifactorial, and the presence of insulin resistance is recognized as the pathophysiological hallmark of this condition. Arterial hypertension is referred as an insulin-resistant state, and insulin resistance may substantially contribute to the cardiovascular risk in this disorder. We examined the inter-relationship between insulin sensitivity, adiponectin levels, and NAFLD in hypertensive patients with different circadian blood pressure profiles. METHODS: Eighty never-treated patients with essential hypertension were selected for having a nocturnal decrement of blood pressure that was at least 10% (dippers, n=47) or less than 10% (nondippers, n=33) of daytime values. No patient had diabetes mellitus, obesity, hyperlipidemia, or other risk factors for hepatic disease. The two groups were similar as to sex, age, and BMI. Abdominal fat distribution and NAFLD were assessed by ultrasonography. RESULTS: Hepatic steatosis was detected in 57.5% of all patients. Nondippers showed a higher prevalence of NAFLD than dippers (81.8 vs. 40.4%, P<0.005). Insulin and the homeostasis model of assessment index were higher (P<0.001) and adiponectin was lower (P<0.001) in nondippers than in dippers, whereas no difference was found in regional fat, liver enzymes, and other metabolic parameters. At multivariate analysis, factors independently associated with nondipping were insulin (P<0.05) and adiponectin (P<0.01) with the homeostasis model of assessment index being of borderline significance. CONCLUSION: In the absence of major risk factors for the development of NAFLD, a high prevalence of liver steatosis was associated with insulin resistance and low adiponectin levels in essential hypertensive patients with a nondipping profile.