Nicotinamide mononucleotide increases muscle insulin sensitivity in prediabetic women 

This study published in 2021 over 10-weeks was a randomized, placebo-controlled, double-blind trial. Demonstrated an improvement in muscle insulin sensitivity similar to the improvement observed after ~10% weight loss 

References:

Yoshino, M.,et al (2021). Nicotinamide mononucleotide increases muscle insulin sensitivity in prediabetic women. Science (New York, N.Y.), 372(6547), 1224–1229. https://doi.org/10.1126/science.abe9985