Serum Nitric Oxide as a Biochemical Marker for Diabetic Nephropathy

The realization that diabetic nephropathy is associated with nitric oxide production, create a great incentive to study the level of nitric oxide in diabetic patients and to ascertain its relation with renal impairment. This study aimed to find out whether serum nitric oxide can be considered as a biochemical marker in diabetic nephropathy. A total of 240 subjects (age and sex matched) were enrolled in this study and divided into two groups; diabetic group included 120 diabetic patients (type 1 and type 2) and control group included 120 apparently healthy subjects. Blood samples were collected from all the individuals and laboratory measurements for HbA1c, serum glucose, urea, creatinine and nitric oxide were done. Urine samples were also collected for measurement of microalbuminuria. The patients were classified into three main groups on the basis of blood pressure and nephropathy. Group 1: Diabetic, normotensive patients; Group 2: Diabetic, hypertensive patients; Group 3: Diabetic, hypertensive patients with nephropathy then group 3 was divided into 3 subgroups according to the stage of diabetic nephropathy: Diabetic incipient nephropathy, diabetic overt nephropathy and diabetic with end stage renal disease. The mean value of serum nitric oxide level was significantly lower in diabetic patients when compared to controls (26.1±1.37 µmol/l) for diabetic normotensive patients, (15.2±0.97 µmol/l) for diabetic hypertensive patients, and (17.4±17.5 µmol/l for diabetic hypertensive patients with nephropathy versus 30.6±2.18 µmol/l for healthy controls). The mean serum nitric oxide (50.9±1.89 µmol/l) and glomerular filtration rate (132±13.9 ml/min), were significantly higher in diabetic patients with early nephropathy (Diabetic incipient nephropathy) than diabetic overt nephropathy (10.1±1.32µmol/l and 44.5±6.36 ml/min), and diabetic with end stage renal disease ((4.9±0.63 µmol/l and 10.5±3.16 ml/min). It is evident from the present study that serum nitric oxide is the major biochemical marker for microvascular complications of diabetes mellitus such as nephropathy. The data support the use of raised serum nitric oxide as a marker for early incipient diabetic nephropathy and a low serum nitric oxide for overt and end stage diabetic nephropathy. The decreases being proportionate to the degree of renal impairment.