In a subsequent single-centre, randomised, placebo controlled-trial, aimed at recruiting 40–50 DMD patients, the same group is currently investigating the efficacy of combined ʟ-citrulline and metformin (NCT01995032; [36]) – ʟ-citrulline was chosen for this trial it is an ʟ-arginine precursor that can demonstrably restore muscular ʟ-arginine levels and reduce muscle wasting in ʟ-arginine-deficient conditions, while having a self-mediated effect on protein metabolism via inducible (i)NOS which bypasses the obvious nNOS deficiency [37]. The gene discussed is NOS1; the disease is Duchenne muscular dystrophy.