The Effects of Blocking Angiotensin Receptors on Endothelial Dysfunction in Type 1 Diabetes
Introduction: Inhibition of the renin-angiotensin system (RAS) may be effective partly in preventing diabetic nephropathy through improving responsible mechanisms. However, there is limited evidence about such beneficial effects in those patients with early stage of DN. This study aimed to investigate the beneficial effects of angiotensin receptor blockers on markers of endothelial function in patients with early stage of DN. Methods: This cross sectional study was carried on 32 participants with type 1 diabetes (IDDM) from January 2010 to May 2011. The participants were candidate for receiving ARBs or ACEIs to decrease microalbuminuria. The inclusion criteria were as follows: The age of onset of IDDM less than 15 years; normal glomerular filtration rate (GFR); normal blood pressure; normal cardiovascular examination; negative urine culture, receiving no medications except insulin. Microalbuminuria was measured in two fasting urine samples with a sampling interval of 1-2 month by ELISA method. Microalbumin to creatinine ratio equaled to or more than 30 mg/gm was considered abnormal. The urine and blood sample to determine urine microalbumin and serum NO and VCAM were obtained at the time 0 (before starting the study), and after 2 months of receiving the medication. Colorimetric assay kit (Cayman, USA) and ELISA kit (Bendermed, UK) were used to measure NO and VCAM, respectively. Valsartan tablet (Diovan, angiotensin receptor blocker from Novartis Company) with a dose of 1 mg/kg/day up to 80 mg/day in a single dose was administered. Results: Urine microalbumin to creatinine ratio after Valsartan consumption was lower than microalbumin level before the medication, P< 0.05. After valsartan consumption, serum VCAM- 1level reduced and NO level increased significantly, P<0.05. Conclusion: Angiotensin receptor blocker (valsartan) reduces VCAM-1 and microalbuminuria and increases NO levels in early stages of DN. Thus administration of ARBs might be considered even in early stages of DN.