Effect of long-term oral glutathione supplementation on gut microbiome of type 2 diabetic individuals.

The aim of this study was to check the effect of long-term oral glutathione (GSH) supplementation on alteration in gut microbiome of Indian diabetic individuals. Early morning fresh stool sample of diabetic individuals recruited in a randomized clinical trial wherein they were given 500 mg GSH supplementation orally once a day for a period of 6 months was collected and gut microbiome was analysed using high throughput 16S rRNA metagenomic sequencing. Long-term GSH supplementation as reported in our earlier work showed significant increase in body stores of GSH and stabilized decreased glycated haemoglobin (HbA1c). Analysis of gut microbiome revealed that abundance of phylum Proteobacteria significantly decreased (P < 0.05) in individuals with GSH supplementation after 6 months compared to those without it. Beneficial dominant genera such as Megasphaera, Bacteroides, and Megamonas were found to be significantly enriched (P < 0.05), while pathogenic Escherichia/Shigella was found to be depleted (P < 0.05) after supplementation. Data clearly demonstrate that GSH supplementation along with antidiabetic treatment helps restore the gut microbiome by enriching beneficial bacteria of healthy gut and reducing significantly the load of pathogenic bacteria of diabetic gut.

Genetic polymorphisms in Nrf2 and FoxO1: implications for antioxidant enzyme activity in diabetes.

In diabetes, persistent hyperglycemia generates excess reactive oxygen species (ROS), leading to oxidative stress (OS). In response to OS, transcription factors (TFs) Nrf2 and FoxO1 get activated, which induce the expression of antioxidant enzymes catalase (CAT) and superoxide dismutase (SOD). It is well documented that the antioxidant response in diabetic individuals is very low. Since Nrf2 and FoxO1 are the major TFs activating these genes, we were interested in determining if single nucleotide polymorphisms (SNPs) in genes for these TFs have any association with lowered antioxidant enzyme activity in diabetic individuals. The activity of CAT and SOD and total antioxidant capacity (TAC) were quantified from the serum samples of diabetic (n = 98) and non-diabetic (n = 90) individuals. Genomic DNA was isolated, and Nrf2 and FoxO1 were amplified and sequenced by Illumina NextSeq500. Data were screened for SNPs in amplified regions. An independent samples t-test to find an association between CAT, SOD, and TAC and allele frequency of SNP with the diabetic condition was carried out. We found decreased CAT and SOD activity and significantly low TAC in diabetic individuals. Thirty-two and thirty-four SNPs and Single-nucleotide variants (SNVs) were observed in Nrf2 and FoxO1, respectively. However, a statistically significant difference in the allele frequency distribution between study groups was observed only in two intronic SNPs, rs17524059:A > C and rs60373589:Indel(A) of Nrf2 and FoxO1, respectively. SNPs, rs17524059 in the Nrf2 and rs60373589 of FoxO1, were not associated with reduced CAT and SOD activity and level of TAC in Indian diabetic individuals.Communicated by Ramaswamy H. Sarma.

Randomized Clinical Trial of How Long-Term Glutathione Supplementation Offers Protection from Oxidative Damage and Improves HbA1c in Elderly Type 2 Diabetic Patients.

Complications in type 2 diabetes (T2D) arise from hyperglycemia-induced oxidative stress. Here, we examined the effectiveness of supplementation with the endogenous antioxidant glutathione (GSH) during anti-diabetic treatment. A total of 104 non-diabetic and 250 diabetic individuals on anti-diabetic therapy, of either sex and aged between 30 and 78 years, were recruited. A total of 125 diabetic patients were additionally given 500 mg oral GSH supplementation daily for a period of six months. Fasting and PP glucose, insulin, HbA1c, GSH, oxidized glutathione (GSSG), and 8-hydroxy-2-deoxy guanosine (8-OHdG) were measured upon recruitment and after three and six months of supplementation. Statistical significance and effect size were assessed longitudinally across all arms. Blood GSH increased (Cohen's d = 1.01) and 8-OHdG decreased (Cohen's d = −1.07) significantly within three months (p < 0.001) in diabetic individuals. A post hoc sub-group analysis showed that HbA1c (Cohen's d = −0.41; p < 0.05) and fasting insulin levels (Cohen's d = 0.56; p < 0.05) changed significantly in diabetic individuals above 55 years. GSH supplementation caused a significant increase in blood GSH and helped maintain the baseline HbA1c overall. These results suggest GSH supplementation is of considerable benefit to patients above 55 years, not only supporting decreased glycated hemoglobin (HbA1c) and 8-OHdG but also increasing fasting insulin. The clinical implication of our study is that the oral administration of GSH potentially complements anti-diabetic therapy in achieving better glycemic targets, especially in the elderly population.