Recent studies have suggested that NNMT activity was increased in obesity and type 2 diabetes mellitus in mice and humans.4, 5, 6 Our recent epidemiological study also revealed that serum me‐NAM, an indicator of NNMT activity, was associated with obesity and diabetes mellitus in a Chinese population.7 Because obesity and diabetes mellitus were independent risk factors for the development of CAD,8, 9 we hypothesized that increased serum me‐NAM levels might be associated with CAD. This evidence concerns the gene NNMT and obesity due to melanocortin 4 receptor deficiency.