Serum and Urinary Nitrites and Nitrates and Doppler Sonography in Detection of Early Diabetic Complications

Abstract

Objective: to evaluate serum and urinary nitrite and nitrate concentrations as an index of nitric oxide (NO) production in type1diabetes mellitus (T1DM) and to investigate the possible alteration and correlation with intra renal Doppler resistive indexes (RIs). Design: The study included 90 children and adolescent with T1DM divided into 2 groups: Group 1: included 45 prepubertal type1 diabetics who were defined as Tanner stage1. Their age ranged between 8-14 years. Group 2: included 45 pubertal type diabetics who were defined as Tanner stages 2-5. Their ages ranged between 15-19 years. They were compared to 45 age and sex matched healthy controls. Clinical examination was done. Laboratory investigations included; post-prandial blood glucose (PPBG), glycosylated heamoglobin (HbA1C), Fundus examination, urinary microalbumin and measurement of serum and urinary nitrite and nitrate levels. Doppler ultrasonographic registration of intrarenal RIs were performed. Results: Compared to controls, both diabetic groups had significantly increased concentrations of serum (P=0.001) and urinary NO (P=0.008).Doppler RIs values were significantly elevated in both diabetic groups compared to controls (P<0.001).A significant positive correlation was found between serum and urinary NO levels (P<0.001). Serum NO was positively correlated with Doppler RIs (P=0.002), HbA1c (P=0.012), PPBG (P=0.000) and diabetes duration (P=0.004). Doppler RIs were positively correlated with mean HbA1c (P=0.025), PPBG (P=0.001) and diabetes duration (P=0.000). Conclusion: In type 1 diabetes chronic hyperglycemia may act through a mechanism that involves increased NO production or action and contributes to generating intrarenal hemodynamic abnormalities which could be detectable by Doppler ultrasonography even before overt clinical nephropathy. Further follow up studies are needed to document the usefulness of Doppler ultrasound in detection of preclinical nephropathy.