Comment on "Nicotinamide mononucleotide increases muscle insulin sensitivity in prediabetic women".

Yoshino et al (Reports, 11 June 2021, p. 1224) have reported that nicotinamide mononucleotide (NMN) increases muscle insulin sensitivity in prediabetic women. However, the 13 women who received NMN had hepatic lipid content of 6.3 ± 1.2%, whereas the 12 in the placebo group had 14.8 ± 2.0% (P = 0.003). Given that a target of NMN is liver fat clearance, this was not an effectively randomized trial.