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Impaired insulin action, frequently found in essential hypertension (HT), is modified by other factors, such as higher age, accumulation of body fat, dyslipidaemia, impaired glucose metabolism and endothelial dysfunction. In addition, antihypertensive and insulin-sensitizing medication itself may significantly affect cardiovascular and metabolic milieu. The aim of this study was to assess insulin sensitivity, acute insulin response, lipidaemic status and the adipokines' concentrations with regard to abdominal fat distribution in young, lean male subjects with treatment-naïve essential HT and in matched healthy normotensive (NT) subjects. We studied 27 HT patients (age: 19.9±0.6 years; body mass index (BMI): 22.9±0.5 kg m(-2)) and 15 NT controls (age: 22.3±1.0 years; BMI: 23.7±0.6 kg m(-2)). The subjects underwent an oral and an intravenous glucose tolerance test (OGTT, IVGTT) on separate days in random order. Higher fasting insulin (P<0.001), non-esterified fatty acids (P<0.05) and plasminogen activator inhibitor factor 1 concentrations (P<0.05) were found in HT patients when compared with NT patients. Despite comparable anthropometric parameters and body fat distribution assessed by magnetic resonance imaging in both groups, newly diagnosed untreated young hypertensive male subjects showed decreased insulin sensitivity, augmented insulin response to both oral and intravenous glucose load (P<0.01; P<0.05 respectively) and 'higher still normal' 2-h plasma glucose levels during OGTT. Untreated, young, lean hypertensive male subjects, with distribution of abdominal adipose tissue and lipid profile comparable with their healthy NT matched counterparts, showed considerable signs of insulin resistance and hyperinsulinaemia. We hypothesize that insulin resistance is the initial feature, which is influenced by several environmental factors, and HT is one of their common consequences.

The interrelationship between activity of sympathetic nervous system and metabolic risk factors in youth with hypertension (HT) has been poorly studied. The aim of our present study was to assess the interrelationship between metabolic risk factors, such as insulin resistance, concentration of plasminogen activator inhibitor (PAI)-1, and catecholamines in an early stage of HT onset. An oral glucose tolerance test was performed in 17 young males with early-diagnosed nontreated HT grade 1 and 16 gender-, age-, and BMI-matched normotensive controls. Concentrations of glucose, insulin, epinephrine, norepinephrine, PAI-1, and plasma renin activity (PRA) were determined in venous plasma. Insulin sensitivity indices (ISIs) proposed by Cederholm, Matsuda, and Gutt were calculated. HT had higher baseline levels of norepinephrine, insulin (P= 0.02), and PAI-1 (P= 0.04). ISIs were lower in HT subjects (P < 0.001). Baseline concentrations of epinephrine were negatively associated with HDL cholesterol (r=-0.415, P= 0.02), ISI Matsuda (r=-0.361, P= 0.04), ISI Cederholm (r=-0.354, P= 0.04), and ISI Gutt (r=-0.429, P= 0.01), and positively with PRA (r= 0.609, P < 0.0001). Positive association was found between baseline concentrations of norepinephrine and PAI-1 (r= 0.418, P= 0.02). The sympathetic overactivity, which occurs in the early stage of HT may contribute to reduced insulin sensitivity even in young patients and intensify the undesirable development of metabolic cardiovascular risk factors and progress of the disease.

Essential hypertension is associated with changes in central catecholaminergic pathways which might also be reflected in the pituitary response to stress stimuli. The aim of this study was to determine whether the response of pituitary hormones, cortisol, plasma renin activity, aldosterone and catecholamines to insulin-induced hypoglycaemia is changed in hypertension. We studied 22 young lean male patients with newly diagnosed untreated essential hypertension and 19 healthy normotensive, age- and body mass index (BMI)-matched controls. All subjects underwent an insulin tolerance test (0.1 IU insulin/kg body weight intravenously) with blood sampling before and 15, 30, 45, 60 and 90 min after insulin administration. Increased baseline levels of norepinephrine (P<0.05), increased response of norepinephrine (P<0.001) and decreased response of growth hormone (P<0.001), prolactin (P<0.001), adrenocorticotropic hormone (P<0.05) and cortisol (P<0.001) were found in hypertensive patients when compared to normotensive controls. Increased norepinephrine levels and a decreased pituitary response to metabolic stress stimuli may represent another manifestation of chronically increased sympathetic tone in early hypertension.

A correction to the article "Insulin resistance in young, lean male subjects with essential hypertension" is presented.