Glutathione and type 2 diabetes: a UWI Mona study and the human data

Glutathione is a tripeptide (glutamate, cysteine and glycine) and the body's most abundant intracellular antioxidant¹⁰. A study from the University of the West Indies (UWI), Mona has put it in a different light: as a candidate add-on in type 2 diabetes, a disease that affects 11.6% of Jamaicans according to figures reported with the study². This article sets out what the Jamaican work found, what it did not test, and what the human evidence says.

The UWI Mona study

The research, led by Amarley Wright, a master's graduate of UWI Mona's Faculty of Medical Sciences, is titled "Combined Supplementation of S-Nitro glutathione and Glutathione Improves Glycaemic Control in type 2 Diabetic Rats"¹. It won the Best Student Oral Presentation award at the 14th Annual National Health Research Conference in 2023¹³.

According to the Jamaica Information Service, glutathione alone significantly reduced blood sugar in the diabetic rats, and combining it with S-nitrosoglutathione (glutathione bound to nitric oxide) produced an "even more pronounced reduction in the blood glucose concentration"¹. Insulin concentration rose compared with untreated rats, and food and fluid intake fell¹. The reports give no numerical results¹²³.

Wright was clear about the limits. He said "further work needs to be done", including on toxicity and mechanisms¹³. The reports note that while human trials of the combination have begun in India, "Jamaica currently has no such programme"¹³. He suggested engaging the Faculty of Medical Sciences' clinical research unit as a next step¹. We looked at why Jamaica has so few home-grown trials in our article on clinical trials law in Jamaica.

Why glutathione is studied in diabetes

The biological case is strong. In a stable-isotope study published in Diabetes Care, people with uncontrolled type 2 diabetes had much lower red-cell glutathione than controls and severely reduced glutathione synthesis, with higher oxidative stress and lipid peroxides⁴. After two weeks of dietary cysteine and glycine, the precursors of glutathione, synthesis and concentrations rose and oxidative stress fell, even with persistent hyperglycaemia⁴. The same Baylor group found a similar synthesis defect in older adults that was corrected by the same precursors⁵, and a later randomised trial of glycine plus N-acetylcysteine (GlyNAC) in older adults reported improvements in glutathione, oxidative stress, insulin resistance and physical function over 16 weeks¹³.

What human trials of glutathione show

• Absorption is debated. A 1992 study in seven volunteers found that a single oral dose did not raise plasma glutathione and concluded that systemic availability "is negligible in man"⁹.
• Longer use may be different. A 6-month randomised trial in 54 healthy adults found that daily oral glutathione raised levels in blood, red cells, plasma and lymphocytes, which returned to baseline after a 1-month washout⁸.
• But not always. A 4-week randomised trial in 40 healthy volunteers found no change in oxidative stress markers or in glutathione status¹².
• In type 2 diabetes, a 6-month trial in India added oral glutathione to antidiabetic treatment in 125 patients; blood glutathione rose and DNA oxidation fell, HbA1c was maintained overall, and a significant HbA1c fall was found only in a post hoc subgroup over 55 years⁶. The same trial reported shifts in the gut microbiome⁷.
• Reviews agree the data are early. A 2026 review in Nutrients called the findings in type 2 diabetes "preliminary and heterogeneous" and said rigorous trials are needed¹⁰.

What it means for Jamaican physicians

The UWI Mona result is a promising animal finding, not a treatment. No human study has yet tested glutathione with S-nitrosoglutathione in Jamaican patients¹. The human glutathione data in diabetes come mainly from one trial in India, with the clearest effect in a subgroup⁶. Patients who ask about glutathione as an add-on deserve that context. Where a glutathione product is sold as a drug, Jamaica's Food and Drugs Regulations also bar anyone from advertising it without the Minister's written approval¹⁴.