Renal hemodynamics in patients with resistant hypertension and type 2 diabetes mellitus

Aim    To study renal hemodynamics in patients with resistant arterial hypertension (RAH) in combination with type 2 diabetes mellitus (DM2) and to identify factors involved in the increase in intrarenal vascular resistance.Material and methods    This study included 59 patients (25 men) with RAH in combination with DM2. Mean age of patients was 60.3±7.9 years; 24-h blood pressure (24-BP) (systolic, diastolic, SBP/DBP) was 158.0±16.3 / 82.5±12.7 mm Hg during the treatment with 4.3 [4.0;5.0] antihypertensive drugs; glycated hemoglobin (HbA1c) was 7.5±1.5 %; estimated glomerular filtration rate (eGFR) was 73.1±21.8 ml/min / 1.73 m2 (CKD-EPI equation). Measurement of office BP, 24-h BP monitoring, renal artery (RA) Doppler, routine lab tests including determination of GFR (CKD-EPI), 24-h urine albumin excretion, and ELISA measurement of blood lipocalin-2, cystatin C, high-sensitive C-reactive protein (hsCRP), and asymmetric dimethylarginine (ADMA) were performed for all patients.Results    Incidence of increased RA resistive index (RI) was 39% despite the high rate of vasodilator treatment (93% for renin-angiotensin-aldosterone system inhibitors, 78% for calcium antagonists). According to a correlation and regression analysis, RA RI values were correlated with the kidney function (r=-0.46, p<0.001 for eGFR, r=0.56; p=0.006 for lipocalin-2), age (r=0.54, p<0.001), increases in concentrations of hsCRP (r=0.35, p<0.001) and ADMA (r=0.39, p=0.028), the increase in vascular stiffness (r=0.59, p<0.001 for pulse BP (PBP) as well as DM2 duration, and HbA1c (r=0.33, p<0.001 for both). The independent association of RA RI with the age, PBP, and duration of DM2 was confirmed by the results of multivariate regression analysis. According to the ROC analysis, the threshold level of RA RI corresponding to a decrease in GFR <60 ml / min / 1.73 m2 was ≥0.693 conv. units.Conclusion    In more than one third of patients with RAH in combination with DM2, increased renal vascular resistance was documented, which was closely associated with impaired kidney function, age, DM2 duration and severity, and markers of low-grade inflammation, endothelial dysfunction, and vascular stiffness. The value of RA RI ≥0.693 conv. units was a threshold for the development of chronic kidney disease (CKD).