Background Hyperinsulinemia is one of the risk factors for unfavourable course ofprimary arterial hypertension, whose effect on the development of complications is still unclear. The purpose of the study was to evaluate the relationship between hyperinsulinemia and the features of left ventricular hypertrophy as well as selected biochemical parameters of renal function. To determine the role of chronic, increased insulin secretion in primary arterial hypertension we compared the effect of hypertension duration on the above mentioned phenomena in groups with high and low insulin secretion.
Methods The study population consisted of 110 men with primary arterial hypertension, of whom 71 patients with mild to moderate hypertension were submitted for final statistical analysis. In each patient a case history, physical examination, insulinemia during oral glucose tolerance test (OGTT), blood pressure measurements (conventional and noninvasive using ABPM), ECG at rest and after exercise, echocardiograms and selected biochemical tests including creatinine and urea were obtained.
Results Based upon the sum of insulin secreted during OGTT the patients were divided into those with high (group II, n = 24) and low insulin secretion (group I, n = 47). Analysis of ABPM measurements revealed higher mean systolic (153.9 mm Hg vs 142.3 mm Hg; p < 0.001) and diastolic blood pressure in the entire 24 hrs (97.8 mm Hg vs 92.8 mm Hg; p < 0.05) in group II as compared with group I, and higher mean systolic and diastolic blood pressure in the day- and nighttime. In the group with high insulin secretion systolic blood pressure variability was also higher at night. Group II was also characterised by higher mean left ventricular mass and left ventricular mass index (LVM = 314.2 g vs LVM1= 254.9 g; p < 0.001; LVMI = 149.0 g/m2 vs LVMI = 128,4 g/m2; p < 0.01 ). In the group with high insulin secretion there was a positive correlation between the duration of hypertension and plasma creatinine concentration (r = 0.42; p < 0.05), ventricular septum thickness at systole (r = 0.43; p < 0.05), left ventricular mass (r = 0.57; p < 0.01) and left ventricular mass index (r = 0,52; p < 0.01). In the whole group of patients insulinemia during OGTT correlated positively with left ventricular posterior wall thickness and ventricular septum thickness both at systole (r = 0.25, p < 0.05; r = 0.27, p < 0.05) and diastole (r = 0.24, p<0.05; r = 027, p < 0.05), left ventricular mass (r = 0.33; p < 0.01) and left ventricular mass index (r = 0.26, p < 0.05).
Conclusion The present study indicates a clear relationship between insulinemia, the features of left ventricular hypertrophy and creatinine concentration. The duration of hypertension in patients with hyperinsulinemia was found to affect the morphology of the left ventricle. It was also observed that plasma creatinine concentration correlated positively with the duration of hypertension associated with hyperinsulinemia. The present findings indicate an unfavourable role of chronic hyperinsulinemia in the development of organ complications in arterial hypertension, including the development of renal failure.