The urea sensor becomes indispensable in diabetics monitoring to predict the nature and cause of diabetes and also as a direct indication for the onset of kidney failure or liver malfunction. The normal level of urea in serum is 8–20 mg/dl (1.3 to ∼3.5 mM). An increase in urea concentration causes renal failure (acute or chronic), urinary tract obstruction, dehydration, shock, burns and gastrointestinal bleeding, whereas a decrease in urea concentration causes hepatic failure, nephrotic syndrome, cachexia (low-protein and high-carbohydrate diets).