Metformin Alone and in Combinations Alter the Methylation Patterns of ABCG1 and TXNIP Loci in Patients of Type 2 Diabetes

Background: DNA methylation, being a predictor of gene-environment interaction, a dynamic and reversible process, and a target of drugs, may help clinicians to step towards precision medicine. Epigenome-wide association studies have linked methylation changes with type 2 diabetes and glycemic control; among such frequently documented differentially methylated loci include TXNIP (Thioredoxin interacting protein) and ABCG1 (ATP-binding cassette Subfamily G Member 1). However, research evaluating the effects of antidiabetic treatment on DNA methylation is quite meager. Objective: The current study aimed to evaluate the pre-and post-treatment methylation status of ABCG1 and TXNIP loci in individuals diagnosed recently with type 2 diabetes (T2Ds). Method: In this quasi-experimental study, individuals recently diagnosed with T2Ds were recruited from 1st March 2022 to 12th June 2023 from diabetes OPDS/clinics. We included the participants (total n=75) as groups that were prescribed Metformin (Met)alone (n=25), Metformin and Dipeptidyl Peptidase- 4 4 inhibitors in combination (Met+DDP4I) (n=25), and Metformin andSodium-Glucose co-Transporter 2 Inhibitors in combination (Met+SGLT2I) (n=25). The methylation status of TXNIP and ABCG1 for all the study groups was evaluated by methylation-specific qPCR. Paired T-test and ANOVA were applied to compare the preand posttreatment methylation status of the study groups. Pearson’s correlation test followed by multiple linear regression analysis was performed to analyze the respective correlations and effect of different independent variables on the outcome of the study i.e., post-treatment methylation percentages of ABCG1 and TXNIP. Results: In all groups, post-treatment ABCG1 methylation was found to be significantly decreased, post-treatment TXNIP methylation displayed a significant increase. In a model of linear regression, among various dependent variables, BMI was observed to significantly influence post treatment ABCG1 methylation in all groups, including Met alone(β=0.788, p=0.002), Met+DDP4I, (β= 0.754, p=0.04) and Met+SGLT2I(β= 0.733, p=0.027), while post-treatment TXNIP methylation was significantly affected by reduction in HbA1c levels in all groups, Met alone (β= -0.999, p <0.001), Met+DDP4I (β= -0.850 p <0.001)and Met+SGLT2I (β= -1.007,p <0.001). Conclusion: Metformin alone and its combinations with DDP4I and SGLT2I decrease the methylation of ABCG1, while increasing the methylation of TXNIP in patients with type 2 diabetes. The post-treatment ABCG1 methylation is associated with a decrease in BMI, whereas the post-treatment TXNIP methylation is associated with a decrease in HbA1c levels. Considering the effects of antidiabetic drugs on the methylation status of aforementioned loci involved in the control of glycemic and metabolic parameters; the results of the current study may pave a path for the implementation of precision medicine in type 2 diabetes after further validation by large scale clinical studies.