# NMN made aging muscle 25% more responsive to insulin URL: https://sciencebased.news/nmn/ Published: 2026-10-18 Updated: 2026-10-30 Claim: NMN raises your NAD+ and makes your muscles respond better to insulin as you age. Grade: Promising What to do: - The best trial used 250 mg of NMN a day for 10 weeks, in women with prediabetes, average age 62. Other trials used 250 to 900 mg a day for 6 to 12 weeks. - Expect a change you cannot feel. Muscle took up 25% more sugar under insulin, but fasting blood sugar and HbA1c did not move. Gains in walking speed were small and not yet confirmed. - Buy a brand that shows a lab test of its batch. In a 2024 test of 18 NMN products, 3 had no NMN at all and only 7 were within 10% of the label. - Safety: small trials found no serious side effects at up to 900 mg a day for 60 days. Nobody has tested years of use. If you take a diabetes drug, tell your doctor. - Not proven: that NMN builds muscle or strength (a 2025 review of the trials found no effect), helps people with normal blood sugar, or makes anyone live longer. # NMN made aging muscle 25% more responsive to insulin *Evidence check, October 18, 2026. Updated October 30, 2026.* > **The claim:** "NMN raises your NAD+ and makes your muscles respond better to insulin as you age." > > **Our grade: Promising.** In a careful, government-funded trial, 250 mg of NMN a day for 10 weeks made the muscle of 25 older women with prediabetes take up 25% more sugar under insulin. It is one small trial, blood sugar tests did not change, and other trials found no gain in muscle or strength. ![A woman in her mid 60s with short gray hair in a pharmacy aisle reads the label of a white bottle marked NMN](https://sciencebased.news/images/nmn-hero.jpg) Ruth is 65. Her last blood test put her sugar in the prediabetes range, and her brother has started taking NMN because David Sinclair does. Would a capsule do anything for her? In 2021 a team at Washington University in St. Louis tested exactly that, in 25 women much like Ruth, with the most exact test of insulin there is [3]. ## Where the claim came from NAD+ is a small molecule every cell uses to turn food into energy and to repair itself, and levels fall with age. NMN (nicotinamide mononucleotide) is a vitamin B3 relative the body turns into NAD+. Food gives you less than 2 mg a day; capsules hold 50 to 150 mg [3]. Harvard's David Sinclair made it famous. On the Huberman Lab podcast in December 2021 he said that he and his 82-year-old father "take a gram of NMN every day" [1]. In a 2025 re-cut of the episode he said that after about two weeks "you'll double, on average double your NAD levels in the blood", and that without it he starts to feel 50 years old: "It may be placebo, but who knows?" [2] In mice, raising NAD+ made the body handle sugar better [3]. Would it do the same in people, and would they notice? ## Muscle took up 25% more sugar The Washington University trial enrolled 25 women past menopause, average age 62, who were overweight and had prediabetes [3]. Thirteen took 250 mg of NMN a day for 10 weeks and 12 took a look-alike placebo, with neither they nor the researchers knowing who got what. The US National Institutes of Health paid for it; a Japanese maker, Oriental Yeast, supplied the capsules. The team used the clamp test, the gold standard for insulin. Insulin runs into a vein for hours while sugar is dripped in to hold blood sugar steady; the more sugar it takes, the better the muscles answer insulin. After 10 weeks of NMN, muscle took up 25% more sugar under insulin than before. On placebo, nothing changed [3]. The authors wrote that the gain was similar to what people get from losing about 10% of their body weight. Muscle samples showed why: two proteins that carry insulin's signal inside the cell, AKT and mTOR, were more active. ![Bar chart of muscle insulin sensitivity, measured as sugar taken up during an insulin infusion, before and after 10 weeks. Placebo: about 50 before and 49.5 after. NMN: about 46.5 before and 57 after, 25% higher. Redrawn from Yoshino et al., Science 2021.](https://sciencebased.news/images/nmn-chart.png) *Redrawn from Figure 2A of the 2021 Washington University trial; group averages read off the figure, the 25% from its text [3].* One result did not fit. The amount of NAD+ in the muscle did not rise. What rose were the leftovers from breaking NAD+ down, which suggests muscle used it faster rather than storing more [3]. So the capsules changed how muscle works without filling it up, and that raises the next question: does the change show up in anything a person can do? ## Older adults walked a little faster Four more trials tested how well people could walk or run, and each found a hint. In Tokyo, 42 healthy men aged 65 and older took 250 mg a day or placebo for 12 weeks [4]. A supplier mix-up swapped the capsules for 22 of them halfway through, so only 10 per group counted at the end. Those on NMN walked 0.09 m per second faster than at the start, and those on placebo 0.01 slower, a gap too small to be sure of (p = 0.066). Grip strength in the left hand improved, the right did not. Insulin, liver fat and belly fat did not change in these men, whose sugar was normal to begin with. The authors called every result exploratory. In a Meiji trial, 60 Japanese adults aged 65 to 75 took 250 mg a day or placebo for 12 weeks [5]. The main test, stepping in place, showed no difference. A 4-meter walk did: at 12 weeks the NMN group was faster than placebo, which the authors read as holding on to walking speed. They also slept a little better on a questionnaire. Meiji, which makes NMN, paid for it, and three authors work there. In India, 80 adults aged 40 to 65 took 300, 600 or 900 mg a day or placebo for 60 days [6]. In six minutes on a treadmill, the placebo group walked 5 meters further than at the start, the 300 mg group 73 meters, the 600 mg group 145 and the 900 mg group 157. The makers of the product paid for the trial. One red flag: by a blood-test aging score, the placebo group aged 5.6 years in 60 days, which no body does. In China, 48 amateur runners aged 27 to 50 took 300 to 1,200 mg a day for 6 weeks while training [9]. Endurance at a moderate pace rose; VO2 max, the top limit, did not. So the walking results point the same way, but they are small, two were paid for by NMN makers, and none was repeated. Which leaves Ruth's real question: would her blood tests look any better? ## The limits Probably not yet. The insulin result is one trial of 25 women, and nobody has repeated it. The gain was in muscle only: fasting blood sugar, insulin, HbA1c (the three-month sugar average), cholesterol, liver fat and belly fat did not change [3]. Grip and leg strength did not change either. When reviewers pooled the trials in older adults in 2025, NMN made no clear difference to muscle mass, grip or walking speed (0.01 m per second slower, across 4 trials) [7]. Another 2025 review of 12 trials and 513 people found NMN raised NAD+ but barely moved blood sugar or cholesterol, and warned that some reports overstate the benefits [8]. The sister supplement NR did not improve insulin in trials in men [3], and in a 410-person trial in Parkinson's disease, placebo did slightly better; see [our NAD booster check](/nad-boosters/). What is in the bottle matters as much. A 2024 lab test from the National University of Singapore checked 18 NMN products: 3 had none, and only 7 were within 10% of the label [10]. A 2021 test of 22 products from Amazon found 14 with less than 1% of what the label said, though it came from ChromaDex, which sells NR [11]. In the US, the FDA ruled in 2022 that NMN could not be sold as a supplement, then reversed itself on September 29, 2025 [12]. That makes it legal to sell, not proven to work. So back to Ruth. The best evidence says 250 mg a day could make her muscle answer insulin better, by about as much as losing a tenth of her weight, though her blood sugar numbers may not show it. ## Our grade The story has one strong result and several weak ones, so the grade depends on which part of the claim you mean. | Question | Evidence | Grade | |---|---|---| | NMN raises NAD+ in the blood [4, 5, 6, 8] | Many randomized trials, 250 to 900 mg a day | Solid | | NMN makes aging muscle respond better to insulin [3] | 1 randomized trial, 25 women with prediabetes, gold-standard clamp test, government-funded | Promising | | NMN keeps older adults walking faster [4, 5, 6, 7] | 3 small trials, 2 paid for by makers; pooled trials show no difference | Weak | | NMN improves blood sugar and cholesterol tests [3, 8] | 12 trials, 513 people: little change | Weak | | NMN builds muscle or strength [3, 7] | Pooled trials in older adults: no effect on muscle mass or grip | Debunked | | Overall: NMN raises your NAD+ and makes your muscles respond better to insulin as you age | A strong test in one small trial; not yet repeated | Promising | The case for the other side: one trial of 25 people is a small base, and small trials often find effects that shrink later. The gain showed up only in the clamp test. If NMN helped muscle handle sugar in daily life, you might expect HbA1c to drift down too, and in 10 weeks it did not. HbA1c reflects about three months of blood sugar, so 10 weeks is short for it to show a change. What would change the grade: a second trial with a clamp test, in more people and for longer, with HbA1c as a main result. A clear repeat would move it toward Solid; a null result would move it down. ## What this means for you - If you have prediabetes and want to try NMN, the trial behind this grade used 250 mg a day for 10 weeks [3]. Higher doses have not been shown to do more for insulin. - Pick a brand that posts a lab test of its batch, since many bottles hold less than the label says [10, 11]. - Losing weight and exercising have more proof. The NMN gain was about what losing 10% of body weight does [3], and NMN did not lower blood sugar numbers. - Don't count on NMN for strength. Lifting and enough protein build muscle; see [how much protein you need](/protein-target/). - Check your numbers. If you track HbA1c or fasting sugar, keep tracking; NMN did not change them in 10 weeks [3]. ## What's next The insulin trial needs a repeat: more people, longer, and blood sugar as a main result. Until then, the result stands on 25 women. This is part of our series on longevity supplements. See [NAD boosters and the Parkinson's trial](/nad-boosters/), [urolithin A for tired muscles](/urolithin-a/), and whether a [biological age test](/biological-age-tests/) can show if any of this works for you. ## Sources 1. Huberman Lab. Dr. David Sinclair: The Biology of Slowing & Reversing Aging. Podcast episode, December 27, 2021. [hubermanlab.com](https://www.hubermanlab.com/episode/dr-david-sinclair-the-biology-of-slowing-and-reversing-aging) 2. Huberman Lab. Essentials: The Biology of Slowing & Reversing Aging, Dr. David Sinclair. Podcast episode, October 30, 2025. [hubermanlab.com](https://www.hubermanlab.com/episode/essentials-biology-slowing-reversing-aging-dr-david-sinclair) 3. Yoshino M, Yoshino J, Kayser BD, Patti GJ, Franczyk MP, Mills KF, et al. Nicotinamide mononucleotide increases muscle insulin sensitivity in prediabetic women. *Science*, 2021. 25 postmenopausal women, average age 62, randomized, double-blind, placebo-controlled, 10 weeks; funded by the US National Institutes of Health, NMN from Oriental Yeast. [doi:10.1126/science.abe9985](https://doi.org/10.1126/science.abe9985) 4. Igarashi M, Nakagawa-Nagahama Y, Miura M, Kashiwabara K, Yaku K, Sawada M, et al. Chronic nicotinamide mononucleotide supplementation elevates blood nicotinamide adenine dinucleotide levels and alters muscle function in healthy older men. *npj Aging*, 2022. 42 men aged 65 and older, randomized, double-blind, placebo-controlled, 12 weeks; NMN from Mitsubishi Corporation Life Sciences. [doi:10.1038/s41514-022-00084-z](https://doi.org/10.1038/s41514-022-00084-z) 5. Morifuji M, Higashi S, Ebihara S, Nagata M. Ingestion of β-nicotinamide mononucleotide increased blood NAD levels, maintained walking speed, and improved sleep quality in older adults in a double-blind randomized, placebo-controlled study. *GeroScience*, 2024. 60 adults aged 65 to 75, randomized, double-blind, placebo-controlled, 12 weeks; funded by Meiji. [doi:10.1007/s11357-024-01204-1](https://doi.org/10.1007/s11357-024-01204-1) 6. Yi L, Maier AB, Tao R, Lin Z, Vaidya A, Pendse S, et al. The efficacy and safety of β-nicotinamide mononucleotide (NMN) supplementation in healthy middle-aged adults: a randomized, multicenter, double-blind, placebo-controlled, parallel-group, dose-dependent clinical trial. *GeroScience*, 2023. 80 adults aged 40 to 65, randomized, double-blind, placebo-controlled, 60 days; funded by Aba Chemicals and Abinopharm, makers of the NMN tested. [doi:10.1007/s11357-022-00705-1](https://doi.org/10.1007/s11357-022-00705-1) 7. Prokopidis K, Moriarty F, Bahat G, McLean J, Church DD, Patel HP. The effect of nicotinamide mononucleotide and riboside on skeletal muscle mass and function: a systematic review and meta-analysis. *Journal of Cachexia, Sarcopenia and Muscle*, 2025. Meta-analysis of randomized trials in adults with an average age of 60 or more. [doi:10.1002/jcsm.13799](https://doi.org/10.1002/jcsm.13799) 8. Zhang J, Poon ET, Wong SH. Efficacy of oral nicotinamide mononucleotide supplementation on glucose and lipid metabolism for adults: a systematic review with meta-analysis on randomized controlled trials. *Critical Reviews in Food Science and Nutrition*, 2025. 12 randomized trials, 513 people. [doi:10.1080/10408398.2024.2387324](https://doi.org/10.1080/10408398.2024.2387324) 9. Liao B, Zhao Y, Wang D, Zhang X, Hao X, Hu M. Nicotinamide mononucleotide supplementation enhances aerobic capacity in amateur runners: a randomized, double-blind study. *Journal of the International Society of Sports Nutrition*, 2021. 48 runners aged 27 to 50, randomized, double-blind, 6 weeks. [doi:10.1186/s12970-021-00442-4](https://doi.org/10.1186/s12970-021-00442-4) 10. Sandalova E, Li H, Guan L, Raj SD, Lim TG, Tian E, et al. Testing the amount of nicotinamide mononucleotide and urolithin A as compared to the label claim. *GeroScience*, 2024. Lab test of 18 NMN products. [doi:10.1007/s11357-024-01257-2](https://doi.org/10.1007/s11357-024-01257-2) 11. ChromaDex. Quantitative analysis of 22 NMN consumer products. Company report, October 2021; ChromaDex sells NR, a competing product. [s23.q4cdn.com](https://s23.q4cdn.com/937095816/files/doc_downloads/2021/Quantitative-Analysis-of-22-NMN-Consumer-Products-Oct-2021.pdf) 12. US Food and Drug Administration. Response to citizen petitions on NMN, docket FDA-2023-P-0872, September 29, 2025. [regulations.gov](https://www.regulations.gov/document/FDA-2023-P-0872-2754)