Nicotinamide mononucleotide increases muscle insulin sensitivity in women with prediabetes

Studies in rodents have shown obesity and aging impair tissue nicotinamide adenine dinucleotide (NAD+) biosynthesis, which contributes to metabolic dysfunction. The availability of nicotinamide mononucleotide (NMN) is an important rate-limiting factor in mammalian NAD+ biosynthesis. We conducted a 10-week, randomized, placebo-controlled, double-blind trial to evaluate the effect of NMN supplementation on metabolic function in 25 postmenopausal women with prediabetes who were overweight/obese. Insulin-stimulated glucose disposal, assessed by using the hyperinsulinemic-euglycemic-clamp procedure, increased by 25±7% (P<0.01) in the NMN group, which was accompanied by an increase in insulin-stimulated phosphorylation of muscle AKT (P<0.01), whereas neither outcome changed after placebo treatment. Body composition (fat mass, fat-free mass, intra-abdominal fat, intrahepatic triglyceride content) and muscle mitochondrial respiratory capacity did not change after treatment with placebo or NMN. These results demonstrate NMN improves muscle insulin sensitivity in women with prediabetes who are overweight/obese, independent of changes in body composition or mitochondrial function. Overall design: We obtained skeletal muscle samples obtained during the basal period and during the hyperinsulinemic-euglycemic clamp procedure (insulin infusion) from women who prediabetes before and after placebo (n=12) or NMN treatment (n=11).