This article is in PubMed so appears legitimate, but I see the original study was published in PLOS which has been associsted with many dubious 'scientific' reports in the past. The cast of authors is many and varied, except that most of them appear to be administrators, and it is not clear who actually did the study or what institution was running it. It seems to be Baylor University Childrens Dept, and is mainly centered in Jamaica, Funding is declared and valid
Note that the sample size is small. They started with 120 possibles and then eliminated most of the for reasons that they do not fully explain.
I would not accept this study at face value, and it needs in depth peer review to make sure if it is sensible.
The internet is peppered to reprints of this research in ads, journals, press releases etc, so it is certainly popular. It is also fairly singular and seems to be on a pedestal on its own.
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5991679/
I did find another study that seems to be associated but was done for T1D
https://professional.diabetes.org/a...athione-gsh-concentrations-adolescents-type-1
This one seems to be better controlled than the other but is looking at the problem from the other way round (i.e. does better diabetic control raise GSH levels? Study found that short term closed loop control with IV insulin did not raise the GSH levels.
Certainly it would appear from the name that Glutathione is involved with glucose metabolism. We have known for some time that diabetes and oxidative stress are connected, and that GSH is an antioxidant hormone.