INS and prediabetes syndrome: The second human clinical study investigated the effects of NMN intake (250 mg/day) in obese postmenopausal women with prediabetes (NMN = 13, placebo = 12) for 10 weeks in a randomized, placebo-controlled, double-blind trial, reporting that significant improvement was found in protein kinase AKT, mTOR protein, and insulin sensitivity, whereas no significant changes were found in grip strength, fatigability, and recovery from the fatiguing exercise of the leg [23].