Pharmacogenetics of Metformin Transporters Suggests No Association with Therapeutic Inefficacy among Diabetes Type 2 Mexican Patients

Abstract

Mexico has been under official epidemiological alert due to diabetes since 2016. This study presents new information on the frequency and variants of metformin transporters OCT1, OCT2, OCT3, ABCB1, and CYP2C9 variants as well. It also reports the association with HbA1c control on 103 DMT2 patients. They were genotyped through real-time PCR (TaqMan assays) and grouped according to treatment: metformin and metformin + glibenclamide. Metformin plasmatic levels were determined through mass spectrometry. The analysis of HbA1c showed statistical significance across genotypes in polymorphisms rs72552763 (p = 0.022), rs622342 (p = 0.009), rs1128503 (p = 0.021), and rs2032582 (p = 0.009) within the monotherapy group. Bivariate analysis found no association between any polymorphism and HbA1c control. Two logistic regression models accounted for two diplotypes in OCT1 and ABCB1, including statistically significant covariates. The first model yielded significance in age (p = 0.026), treatment period [p = 0.001], BMI ≥ 25 kg/m2 (p = 0.043), and combined therapy (p < 0.001). There was no association with GAT/GAT of rs72552763 or A/A rs622342 in OCT1. The second model yielded significance in age (p = 0.017), treatment period (p = 0.001), BMI ≥ 25 kg/m2 (p = 0.042), and combined therapy (p < 0.001), finding no association with C/C of rs1128503 or G/G of rs2032582 in ABCB1. Our multinomial logistic regression results may benefit future predictive analyses in diabetic populations.

Impact of SLC22A1 variants rs622342 and rs72552763 on HbA1c and metformin plasmatic concentration levels in patients with type 2 diabetes mellitus

“…These results suggest that GAT/GAT patients exhibit stable %HbA1c levels when the metformin dosage increases, whereas del allele carriers exhibit high %HbA1c levels in spite of increased metformin intake. These finds concur with our previous study (15), which reported higher %HbA1c levels in patients with T2DM carrying the del allele (P=0.022). In a prospective study conducted on patients with metformin-treated T2DM from the University Clinical Centre of Sarajevo, Bosnia-Herzegovina by Dujic et al (25), the number of minor alleles of two OCT1 SNPs, including rs72552763, was associated with adverse gastroenteric reaction [OR=2.31 (IC95% 1.07-5.01), P=0.034].…”

“…There are official reports which indicate an HbA1c non-control prevalence of ~75% among patients with T2DM ( 15 , 19 ); the present study reported a non-control prevalence of 29.42% among male and 26.19% among female patients; the difference was not significant. The present study reported an overall non-control prevalence of 27.11%, a lower rate compared with ENSANUT 2012( 18 ).…”

“…Genotyping procedure. Genotyping was performed as previously described (15). A peripheral 10 ml blood sample was collected from all participants in EDTA tubes, and genomic DNA was extracted from 200 µl venous peripheral blood using UltraClean ® BloodSpin ® DNA isolation reagents (Mo Bio Laboratories; Qiagen, Inc.), evaluated for integrity and concentration via 1% agarose electrophoresis and spectrophotometry using NanoDrop™ 2000/2000c (Thermo Scientific, Inc.), respectively.…”

“…Reactions were performed in a final reaction volume of 10 µl with 30 ng genomic DNA template, 1X TaqMan ® Universal PCR Master mix, 1X each probe assessed ( SLC22A1 : rs12208357, C__30634096_10; SLC22A1 : rs2282143, C__15877554_40; SLC22A1 : rs594709, C___1898206_20; SLC22A1 : rs622342, C____928527_30; SLC22A1 : rs628031, C___8709275_60; SLC22A1 : rs683369, C____928536_30; SLC22A1 : rs72552763, C__34211613_10; SLC22A2 : rs316019, C___3111809_20; SLC22A3 : rs2076828, C___2763995_1_ and SLC22A3 : rs8187725, C__30633894_10) and water. Thermocycling conditions and allelic discrimination to identify the genotypes using allelic discrimination software ABI PRISM 700 Sequence Detection System v1.0 (Applied Biosystems; Thermo Fisher Scientific, Inc.) were as previously described ( 15 ). SNP allelic and genotypic frequencies of OCT1, OCT2, and OCT3 were performed by direct counting.…”

Identification of Transporter Polymorphisms Influencing Metformin Pharmacokinetics in Healthy Volunteers

“…Metformin transporters OCT1, OCT2, OCT3, and P-glycoprotein were linked to therapeutic failure in a recent pharmacogenetics investigation of Mexican individuals with type 2 diabetes [ 19 ]. Another study involving 103 patients with type 2 diabetes mellitus revealed no correlation between ABCB1 polymorphism and HbA1c stabilization [ 37 ]. However, in our study, the T/T genotype of ABCB1 rs1128503 polymorphism was related to lower Vd/F and Cl/F.…”