While it can be nothing more than speculation because of the small sample size, patients who showed therapeutic effects following glutathione treatment appeared to be younger and did not have diabetes or had mild diabetes
Foods rich in cysteine and glycine help provide the building blocks needed for glutathione production
Design of such a trial should be given some consideration because the goals here are multiple: first to determine how long the effect would last, second to determine effectiveness of a repeat treatment, and third the general health of the patient and how well they tolerate the repeat treatments
Toxicol Applied Pharmacol 27(2):241-52, 1974) Figure 1
Di Donato P, Giulini NA, Bacchi MA, Cicchetti G, Comitini G, et al