Glucose enters the rbc by an insulin-independent mechanism , and most is metabolized to produce atp and reduced nicotinamide adenine dinucleotide ( nadh ) .
Recent studies have shown that nicotinamide adenine dinucleotide ( nad ) is not only a co-enzyme in cellular oxidation-reduction reactions , but also a substrate for reactions catalyzed by mono ( adp-ribose ) transferases , poly ( adp-ribose ) polymerases and acetylase , and it play important roles in numerous cellular physiologic functions .