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Therapeutic response to metformin, a first-line drug for type 2 diabetes (T2D), is highly variable, in part likely due to genetic factors. To date, metformin pharmacogenetic studies have mainly focused on the impact of variants in metformin transporter genes, with inconsistent results. To clarify the significance of these variants in glycemic response to metformin in T2D, we performed a large-scale meta-analysis across the cohorts of the Metformin Genetics Consortium (MetGen). Nine candidate polymorphisms in five transporter genes (organic cation transporter [OCT]1, OCT2, multidrug and toxin extrusion transporter [MATE]1, MATE2-K, and OCTN1) were analyzed in up to 7,968 individuals. None of the variants showed a significant effect on metformin response in the primary analysis, or in the exploratory secondary analyses, when patients were stratified according to possible confounding genotypes or prescribed a daily dose of metformin. Our results suggest that candidate transporter gene variants have little contribution to variability in glycemic response to metformin in T2D.

Background: There is no doubt that genetic factors have the potential to predict the therapeutic outcomes of antidepressants in patients with major depressive disorder (MDD). This study investigated the association between genetic variants involved in serotonin signaling and brain-derived neurotrophic factor (BDNF) with the response to escitalopram treatment in patients with MDD. We focused on examining the influence of 5-HTTLPR (ins/del), HTR2A rs9316233, BDNF rs962369, CYP2C19 and CYP2D6 on the clinical response to escitalopram., Methods: The patients were recruited from outpatient psychiatric clinics in Košice between 2020 and 2022. Patients received escitalopram for 12 weeks at a fixed dose of 10 mg daily. Clinical assessment was done at baseline and after 4, 8, and 12 weeks using the 21-item Hamilton Depression Rating Scale (HAMD-21)., Results: At the end of week 12, 57 (65%) patients were defined as responders to escitalopram treatment, while 31 (35%) patients were non-responders. Genotyping revealed that carriers of the short allele (S) of 5-HTTLPR exhibit a significantly lower therapeutic response to escitalopram measured by HAMD-21 than the long allele (L) carriers (p = 0.01). Adjusting for CYP2C19 and CYP2D6 metabolizer genotypes did not modify the observed relationship between 5-HTTLPR and treatment response. No significant associations were found for HTR2A rs9316233 or BDNF rs962369 variants and the treatment response., Conclusions: These findings underscore the utility of 5-HTTLPR genotyping in guiding escitalopram therapy for MDD patients. Further research with larger cohorts is warranted to validate these results and elucidate additional genetic determinants of antidepressant efficacy., (© 2024. The Author(s).)

Objective: To determine sex differences in the neurochemical concentrations measured by in vivo proton magnetic resonance spectroscopy ( 1 H MRS) of healthy mice on a genetic background commonly used for neurodegenerative disease models., Methods: 1 H MRS data collected from wild type mice with C57BL/6 or related genetic backgrounds in seven prior studies were used in this retrospective analysis. To be included, data had to be collected at 9.4 tesla magnetic field using advanced 1 H MRS protocols, with isoflurane anesthesia and similar animal handling protocols, and a similar number of datasets from male and female mice had to be available for the brain regions analyzed. Overall, 155 spectra from female mice and 166 spectra from male mice (321 in total), collected from six brain regions (brainstem, cerebellum, cortex, hippocampus, hypothalamus, and striatum) at various ages were included., Results: Concentrations of taurine, total creatine (creatine + phosphocreatine), ascorbate, glucose and glutamate were consistently higher in male vs. female mice in most brain regions. Striatum was an exception with similar total creatine in male and female mice. The sex difference pattern in the hypothalamus was notably different from other regions. Interaction between sex and age was significant for total creatine and taurine in the cerebellum and hippocampus., Conclusion: Sex differences in regional neurochemical levels are small but significant and age-dependent, with consistent male-female differences across most brain regions. The neuroendocrine region hypothalamus displays a different pattern of sex differences in neurochemical levels. Differences in energy metabolism and cellular density may underlie the differences, with higher metabolic rates in females and higher osmoregulatory and antioxidant capacity in males., Competing Interests: The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest. The author(s) declared that they were an editorial board member of Frontiers, at the time of submission. This had no impact on the peer review process and the final decision., (Copyright © 2023 Tkáč, Xie, Shah, Larson, Dubinsky, Gomez-Pastor, McLoughlin, Orr, Eberly and Öz.)

Introduction: Glycated hemoglobin (HbA1c) is a crucial marker of glucose control that is widely utilized in the management of diabetes mellitus. The aim of this study was to evaluate the effect of a diabetes management program (DMP) offered by a health insurance company, together with the effects of other factors associated with patient and physician characteristics, on the frequency of HbA1c testing in outpatient diabetes clinics in Slovakia., Methods: A retrospective analysis was conducted to compare the frequency of HbA1c measurements in patients under the care of physicians participating in the DMP with those who did not, spanning the years 2015 to 2019. In 2019, a total of 74,384 patients with diabetes were included in the analysis, of which 52% were men and 48% were women, with an average age of 64.1 years., Results: At the end of the study period, the average annual number of HbA1c measurements was significantly higher in patients treated by physicians participating in the DMP than in patients treated by physicians who were not (2.50 vs. 1.91 per year, respectively; P < 0.001). There was a substantial increase in HbA1c testing at least twice yearly in both groups, but the growth rate was greater in the group with DMP-engaged diabetologists (14.3%) compared to the diabetes specialists who were not involved in the DMP (5.1%). In the multivariate analysis, participation in the DMP was correlated with an increase in HbA1c tests per year by 0.7., Conclusions: Physician participation in a DMP was found to significantly increase the number of HbA1c tests ordered by physicians, potentially leading to improved glycemic control., (© 2023. The Author(s).)

Introduction: This study aimed to evaluate the effectiveness and safety of switching from basal bolus insulin treatment (BBIT) to a fixed combination of insulin degludec and liraglutide (IDegLira) in patients with type 2 diabetes mellitus (T2DM) who had preserved insulin secretion but inadequate glucose control. The study also aimed to assess the feasibility of implementing this therapeutic approach in common clinical practice settings., Methods: This was a non-randomized, open-label, multicenter, prospective, single-arm study involving 234 patients with T2DM who were receiving BBIT. Inclusion criteria were duration of diabetes mellitus > 60 months, stable total daily dose of insulin (TDDI) ranging from > 20 to < 70 IU/day (approx. > 0.3 to < 0.7 IU/kg body weight/day), C-peptide levels > 10% above the lower limit, HbA1c levels > 7% and < 10% (Diabetes Control and Complications Trial), and body mass index > 25 kg/m 2 . The primary endpoints were changes in glycated hemoglobin (HbA1c) and body weight at week 28 after treatment switching. Secondary endpoints included changes in the 7-point glycemic profile, hypoglycemia frequency, blood pressure, blood lipids, liver enzymes, insulin dose, and a patient questionnaire focusing on treatment satisfaction, concerns and impact on daily activities. A subgroup of 55 patients underwent continuous glucose monitoring (CGM) with the evaluation of CGM-derived parameters, such as time in range (TIR), time above range (TAR), time below range (TBR), hypoglycemia, and glucose variability., Results: A significant decrease in HbA1c (8.6% vs. 7.6%; p < 0.0001) and body weight (97.8 vs. 94.0 kg; p < 0.0001) was observed at week 28 after treatment switching. Significant improvements were also seen in all measurements of the 7-point glycemic profile (p < 0.0001), reduction in the number of hypoglycemia episodes per patient, and the proportion of patients with at least one hypoglycemia event (p < 0.001). Furthermore, there was a significant decrease in daily insulin dose (55.6 vs. 32.7 IU/day; p < 0.0001), as well as improvements in blood pressure, blood lipids, and liver enzymes (gamma glutamyl transferase and alanine aminotransferase). The subgroup of patients who underwent CGM showed a significant increase in TIR (57.9% vs. 69.0%; p < 0.01) and a decrease in TAR (40.1% vs. 28.8%; p < 0.01), while TBR, hypoglycemia (number of episodes per patient and proportion of patients), and glucose variability did not change significantly., Conclusion: The results of this study suggest that switching from BBIT to IDegLira in patients with T2DM and preserved insulin secretion can simplify treatment without compromising glycemic control. The switch to IDegLira was associated with significant improvements in various glucose control parameters, including HbA1c, glycemic profile, hypoglycemia, insulin doses, and CGM-derived parameters TIR and TAR. Additionally, it led to significant reductions in body weight, blood pressure, lipid profile, and liver enzyme levels. Switching to IDegLira may be considered a safe and beneficial approach in clinical practice settings, offering metabolic and individual advantages., (© 2023. The Author(s).)

This study enrolled 291 patients diagnosed with depression and schizophrenia (F32, F33, and F20 according to ICD-10) and 227 ethnicity-matched control subjects. We analyzed the distribution of BDNF rs6265 and BDNF rs962369 genotypes, finding no significant associations between these and schizophrenia. We revealed a significant increase in the risk of single-episode major depression disorder (MDD) for rs962369 minor allele homozygotes (CC vs. TT+TC), an association that persisted after adjusting for age and sex (OR 3.47; 95% CI 1.36-8.85; p = 0.009). Furthermore, rs962369 genotype was significantly associated with an increased risk of recurrent MDD in a log-additive model (OR per C-allele 1.65; 95% CI 1.11-2.45; p = 0.013). A comparative analysis between MDD subtypes and between MDD subtypes and schizophrenia showed no significant differences for BDNF rs6265. Notably, the frequency of minor allele C of BDNF rs962369 varied across subgroups, with the highest frequency in patients with recurrent MDD (0.32) and the lowest in schizophrenia patients (0.20). The presence of genotypes with at least one minor allele C was significantly higher in the recurrent MDD patient group compared to the schizophrenia group. In conclusion, the BDNF rs962369 variant was associated with MDD but not with schizophrenia.

Cardiovascular diseases are among the leading causes of morbidity and mortality, particularly in individuals with type 2 diabetes. There is a need for new biomarkers to improve the prediction of cardiovascular events and overall mortality. We investigated the association of selected atherosclerosis related biomarkers, specifically osteoprotegerin (OPG), 25-hydroxy-vitamin D (25(OH)D), C-reactive protein (CRP), lipopolysaccharide-binding protein (LBP), and asymmetric dimethylarginine (ADMA), with the occurrence of any cardiovascular event or all-cause mortality (primary outcome) during a 5.6-year follow-up of 190 patients with type 2 diabetes. Data were analyzed using logistic regression to adjust for baseline cardiovascular status and cardiovascular risk factors. The primary outcome occurred in 89 participants (46.8%) during the study. When analyzed individually, 25(OH)D, CRP, and LBP significantly predicted the primary outcome in multivariable models. However, in a model that included all biomarkers, only a decreased level of 25(OH)D remained a significant predictor of the primary outcome. Moreover, the level of 25(OH)D significantly predicted all-cause mortality: a reduction of 10 ng/mL was associated with a two-fold increase in all-cause mortality. Our study thus demonstrates that vitamin D deficiency was the strongest factor associated with the primary outcome and all-cause mortality after a 5.6-year follow-up in patients with type 2 diabetes at high cardiovascular risk.

Lactate is used as an energy source by producer cells or shuttled to neighboring cells and tissues. Both glucose and lactate fulfill the bioenergetic demand of neurons, the latter imported from astrocytes. The contribution of astrocytic lactate to neuronal bioenergetics and the mechanisms of astrocytic lactate production are incompletely understood. Through in vivo 1 H magnetic resonance spectroscopy, 13 C glucose mass spectroscopy, and electroencephalographic and molecular studies, here we show that the energy sensor AMP activated protein kinase (AMPK) regulates neuronal survival in a non-cell-autonomous manner. Ampk-null mice are deficient in brain lactate and are seizure prone. Ampk deletion in astroglia, but not neurons, causes neuronal loss in both mammalian and fly brains. Mechanistically, astrocytic AMPK phosphorylated and destabilized thioredoxin-interacting protein (TXNIP), enabling expression and surface translocation of the glucose transporter GLUT1, glucose uptake, and lactate production. Ampk loss in astrocytes causes TXNIP hyperstability, GLUT1 misregulation, inadequate glucose metabolism, and neuronal loss., Competing Interests: Declaration of Interests The authors declare no competing interests., (Copyright © 2020 The Author(s). Published by Elsevier Inc. All rights reserved.)

Aim: We examined associations of eight SNPs in/near seven candidate genes with glycemic response to 6 month treatment with DPP4 inhibitors. Patients & methods: 206 patients with type 2 diabetes (116 men and 90 women) were treated with sitagliptin or vildagliptin (both 100 mg/day) in combination with metformin or metformin/sulphonylurea over 6 months, and the reduction in glycated hemoglobin (HbA 1c ) was measured. Results: Rs6923761 in GLP1R was significantly associated with a reduction in HbA 1c (adjusted p = 0.006). Homozygotes for the minor A allele had smaller reduction in HbA 1c by 0.4% (4 mmol/mol) than the G allele carriers (p = 0.016). Conclusion: The missense variant rs6923761 in the  GLP1R gene was associated with a smaller glycemic response to 6 month gliptin therapy in diabetic patients of central European origin.

Repetitive transcranial magnetic stimulation (rTMS) is a non-invasive brain stimulation method commonly used in the disciplines of neuroscience, neurology, and neuropsychiatry to examine or modulate brain function. Low frequency rTMS (e.g., 1 Hz) is associated with a net suppression of cortical excitability, whereas higher frequencies (e.g., 5 Hz) purportedly increase excitability. Magnetic resonance spectroscopy (MRS) and resting-state functional MRI (rsfMRI) allow investigation of neurochemistry and functional connectivity, respectively, and can assess the influence of rTMS in these domains. This pilot study investigated the effects of rTMS on the primary motor cortex using pre and post MRS and rsfMRI assessments at 7 T. Seven right-handed males (age 27 ± 7 y.o.) underwent single-voxel MRS and rsfMRI before and about 30-min after rTMS was administered outside the scanner for 20-min over the primary motor cortex of the left (dominant) hemisphere. All participants received 1-Hz rTMS; one participant additionally received 5-Hz rTMS in a separate session. Concentrations of 17 neurochemicals were quantified in left and right motor cortices. Connectivity metrics included fractional amplitude of low-frequency fluctuations (fALFF) and regional homogeneity (ReHo) of both motor cortices, strength of related brain networks, and inter-hemispheric connectivity. The group-analysis revealed few trends (i.e., uncorrected for multiple comparisons), including a mean increase in the concentration of the inhibitory neurotransmitter γ-aminobutyric acid (GABA) after the inhibitory rTMS protocol as compared to baseline in the stimulated (left) motor cortex (+8%, p = 0.043), along with a slight increase of total creatine (+2%, p = 0.018), and decrease of aspartate (-18%, p = 0.016). Additionally, GABA tended to decrease in the contralateral hemisphere (-6%, p = 0.033). No other changes of metabolite concentrations were found. Whereas functional connectivity outcomes did not exhibit trends of significant changes induced by rTMS, the percent changes of few connectivity metrics in both hemispheres were negatively correlated with GABA changes in the contralateral hemisphere. While studies in larger cohorts are needed to confirm these preliminary findings, our results indicate the safety and feasibility of detecting changes in key metabolites associated with neurotransmission after a single 1-Hz rTMS session, establishing the construct for future exploration of the neurochemical, and connectivity mechanisms of cortical responses to neuromodulation., (Copyright © 2019 Gröhn, Gillick, Tkáč, Bednařík, Mascali, Deelchand, Michaeli, Meekins, Leffler-McCabe, MacKinnon, Eberly and Mangia.)

Aim: To assess the effects of single nucleotide polymorphisms (SNPs) on blood pressure control in patients with obstructive sleep apnea (OSA)., Methods: This prospective observational cohort study, conducted between 2004 and 2014, examined the associations of SNPs of JAG1, GUCY1A3-GUCY1B3, SH2B3, and NPR3-C5orf23 genes with systolic and diastolic blood pressure (SBP, DBP) in 1179 adults evaluated for OSA with overnight polysomnography. Genotyping was performed by unlabeled probe melting analysis., Results: The patients were predominantly male (69.6%, mean age 52±11 years, apnea-hypopnea index 34±31 episodes/h). Only JAG1 genotype was associated with SBP and DBP: compared with AA homozygotes, G allele carriers (pooled GG and AG genotype) had significantly higher morning SBP (132±19 vs 129±18 mm Hg; P=0.009) and morning and evening DBP (85±11 vs 83±10 mm Hg, P=0.004; 86±10 vs 84±10 mm Hg, P=0.012, respectively); the differences remained significant after the correction for multiple SNPs testing. In multivariate analyses, oxygen desaturation index and JAG1 genotype independently predicted morning SBP (P=0.001, P=0.003, respectively) and DBP (P<0.001, P=0.005, respectively), and evening SBP (P=0.019, P=0.048, respectively) and DBP (P=0.018, P=0.018, respectively)., Conclusion: This is the first replication study of the SNPs recently linked to arterial hypertension in general population by genome-wide association studies. Our findings suggest that JAG1 genotype is related to blood pressure control in OSA: G allele was associated with higher morning and evening SBP and DBP.

EMPA-REG OUTCOME is recognised by international guidelines as a landmark study that showed a significant cardioprotective benefit with empagliflozin in patients with type 2 diabetes (T2D) and cardiovascular disease. To assess the impact of empagliflozin in routine clinical practice, the ongoing EMPRISE study is collecting real-world evidence to compare effectiveness, safety and health economic outcomes between empagliflozin and DPP-4 inhibitors. A planned interim analysis of EMPRISE was recently published, confirming a substantial reduction in hospitalisation for heart failure with empagliflozin across a diverse patient population. In this commentary article, we discuss the new data in the context of current evidence and clinical guidelines, as clinicians experienced in managing cardiovascular risk in patients with T2D. We also look forward to what future insights EMPRISE may offer, as evidence is accumulated over the next years to complement the important findings of EMPA-REG OUTCOME.

In the present study, we aimed at determining the metabolic responses of the human visual cortex during the presentation of chromatic and achromatic stimuli, known to preferentially activate two separate clusters of neuronal populations (called "blobs" and "interblobs") with distinct sensitivity to color or luminance features. Since blobs and interblobs have different cytochrome-oxidase (COX) content and micro-vascularization level (i.e., different capacities for glucose oxidation), different functional metabolic responses during chromatic vs. achromatic stimuli may be expected. The stimuli were optimized to evoke a similar load of neuronal activation as measured by the bold oxygenation level dependent (BOLD) contrast. Metabolic responses were assessed using functional 1 H MRS at 7 T in 12 subjects. During both chromatic and achromatic stimuli, we observed the typical increases in glutamate and lactate concentration, and decreases in aspartate and glucose concentration, that are indicative of increased glucose oxidation. However, within the detection sensitivity limits, we did not observe any difference between metabolic responses elicited by chromatic and achromatic stimuli. We conclude that the higher energy demands of activated blobs and interblobs are supported by similar increases in oxidative metabolism despite the different capacities of these neuronal populations.

Objective: Data on the possible relationship of gliptin treatment with the incidence of acute pancreatitis have been controversial. The aim of the current study was to combine data on the incidence of acute pancreatitis from three large randomized controlled trials., Research Design and Methods: Three trials designed to test cardiovascular safety and efficacy of add-on treatment with a gliptin were included in the analysis, as follows: SAVOR-TIMI 53 (saxagliptin), EXAMINE (alogliptin), and TECOS (sitagliptin). The trials included 18,238 gliptin-treated patients and 18,157 placebo-treated patients. Data were combined using a random-effects model meta-analysis., Results: The incidence of acute pancreatitis was significantly increased in the gliptin-treated patients when compared with the control groups (odds ratio 1.79 [95% CI 1.13-2.82], P = 0.013). The difference in the absolute risk was small (0.13%)., Conclusions: Treatment with gliptins significantly increased the risk for acute pancreatitis in a combined analysis of three large controlled randomized trials., (© 2017 by the American Diabetes Association.)

Proton nuclear magnetic resonance spectroscopy of biofluids has become one of the key techniques for metabolic profiling and phenotyping. This technique has been widely used in a number of epidemiological studies and in a variety of health disorders. However, its utilization in brain disorders is limited due to the blood-brain barrier, which not only protects the brain from unwanted substances in the blood, but also substantially limits the potential of finding biomarkers for neurological disorders in serum. This review article focuses on the potential of localized in vivo proton magnetic resonance spectroscopy ( 1 H-MRS) for non-invasive neurochemical profiling in the human brain. First, methodological aspects of 1 H-MRS (data acquisition, processing and metabolite quantification) that are essential for reliable non-invasive neurochemical profiling are described. Second, the power of 1 H-MRS-based neurochemical profiling is demonstrated using some examples of its application in neuroscience and neurology. Finally, the authors present their vision and propose necessary steps to establish 1 H-MRS as a method suitable for large-scale neurochemical profiling in epidemiological research., (© The Author 2016; all rights reserved. Published by Oxford University Press on behalf of the International Epidemiological Association.)

Incretin effect enhancers are drugs used in the treatment of Type 2 diabetes and include GLP-1 receptor agonists and dipeptidyl peptidase-4 inhibitors (gliptins). Variants in several genes were shown to be involved in the physiology of incretin secretion. Only two gene variants have evidence also from pharmacogenetic studies. TCF7L2 rs7903146 C>T and CTRB1/2 rs7202877 T>G minor allele carriers were both associated with a smaller reduction in HbA1c after gliptin treatment when compared with major allele carriers. After replication in further studies, these observations could be of clinical significance in helping to identify patients with potentially lower or higher response to gliptin treatment.

Several laboratories have consistently reported small concentration changes in lactate, glutamate, aspartate, and glucose in the human cortex during prolonged stimuli. However, whether such changes correlate with blood oxygenation level-dependent functional magnetic resonance imaging (BOLD-fMRI) signals have not been determined. The present study aimed at characterizing the relationship between metabolite concentrations and BOLD-fMRI signals during a block-designed paradigm of visual stimulation. Functional magnetic resonance spectroscopy (fMRS) and fMRI data were acquired from 12 volunteers. A short echo-time semi-LASER localization sequence optimized for 7 Tesla was used to achieve full signal-intensity MRS data. The group analysis confirmed that during stimulation lactate and glutamate increased by 0.26 ± 0.06 μmol/g (~30%) and 0.28 ± 0.03 μmol/g (~3%), respectively, while aspartate and glucose decreased by 0.20 ± 0.04 μmol/g (~5%) and 0.19 ± 0.03 μmol/g (~16%), respectively. The single-subject analysis revealed that BOLD-fMRI signals were positively correlated with glutamate and lactate concentration changes. The results show a linear relationship between metabolic and BOLD responses in the presence of strong excitatory sensory inputs, and support the notion that increased functional energy demands are sustained by oxidative metabolism. In addition, BOLD signals were inversely correlated with baseline γ-aminobutyric acid concentration. Finally, we discussed the critical importance of taking into account linewidth effects on metabolite quantification in fMRS paradigms.

A plethora of magnetic resonance (MR) techniques developed in the last two decades provide unique and noninvasive measurement capabilities for studies of basic brain function and brain diseases in humans. Animal model experiments have been an indispensible part of this development. MR imaging and spectroscopy measurements have been employed in animal models, either by themselves or in combination with complementary and often invasive techniques, to enlighten us about the information content of such MR methods and/or verify observations made in the human brain. They have also been employed, with or independently of human efforts, to examine mechanisms underlying pathological developments in the brain, exploiting the wealth of animal models available for such studies. In this endeavor, the desire to push for ever-higher spatial and/or spectral resolution, better signal-to-noise ratio, and unique image contrast has inevitably led to the introduction of increasingly higher magnetic fields. As a result, today, animal model studies are starting to be conducted at magnetic fields ranging from ~ 11 to 17 Tesla, significantly enhancing the armamentarium of tools available for the probing brain function and brain pathologies.

The impact of type 1 diabetes mellitus (T1DM) on a comprehensive neurochemical profile of the human brain has not been reported yet. Our previous proton magnetic resonance spectroscopy ((1)H-MRS) studies on T1DM were focused exclusively on the assessment of brain glucose levels. In this study, we reexamined our previously acquired data to investigate concentration differences of a broad range of neurochemicals in T1DM subjects relative to nondiabetic controls. We selected MRS data from 13 subjects (4 F/9 M, age = 41 ± 11 years, body mass index = 26 ± 3 kg/m(2)) with well-controlled T1DM (disease duration = 22 ± 12 years, A1C = 7.5% ± 2.0%) and 32 nondiabetic controls (14 F/18 M, age = 36 ± 10 years, body mass index = 27 ± 6 kg/m(2)) acquired during a hyperglycemic clamp (target [Glc]plasma = 300 ± 15 mg/dL). The (1)H-MR spectra were collected from two 15.6-mL voxels localized in gray-matter-rich occipital lobe and in white-matter-rich parieto-occipital region using ultra-short echo-time STEAM at 4 T. LCModel analysis allowed reliable quantification of 17 brain metabolites. Lower levels of N-acetylaspartate (by 6%, P=0.007) and glutamate (by 6%, P=0.045) were observed in the gray matter of T1DM patients as compared with controls, which might indicate a partial neuronal loss or dysfunction as a consequence of long-term T1DM. No other differences in metabolites were observed between subjects with T1DM and controls.

Previous studies showed associations between variants in TCF7L2 gene and the therapeutic response to sulfonylureas. All sulfonylureas stimulate insulin secretion by the closure of ATP-sensitive potassium (KATP) channel. The aim of the present study was to compare TCF7L2 genotype specific effect of gliclazide binding to KATP channel A-site (Group 1) with sulfonylureas binding to AB-site (Group 2). A total of 101 patients were treated with sulfonylureas for 6 months as an add-on therapy to the previous metformin treatment. TCF7L2 rs7903146 C/T genotype was identified by real-time PCR with subsequent melting curve analysis. Analyses using the dominant genetic model showed significantly higher effect of gliclazide in the CC genotype group in comparison with combined CT + TT genotype group (1.32 ± 0.15% versus 0.73 ± 0.11%, P (adj) = 0.005). No significant difference in ΔHbA1c between the patients with CC genotype and the T-allele carriers was observed in Group 2. In the multivariate analysis, only the TCF7L2 genotype (P = 0.006) and the baseline HbA1c (P < 0.001) were significant predictors of ΔHbA1c. After introducing an interaction term between the TCF7L2 genotype and the sulfonylurea type into multivariate model, the interaction became a significant predictor (P = 0.023) of ΔHbA1c. The results indicate significantly higher difference in ΔHbA1c among the TCF7L2 genotypes in patients treated with gliclazide than in patients treated with glimepiride, glibenclamide, or glipizide.

Oral antidiabetic drugs (OADs) are used for more than a half-century in the treatment of type 2 diabetes. Only in the last five years, intensive research has been conducted in the pharmacogenetics of these drugs based mainly on the retrospective register studies, but only a handful of associations detected in these studies were replicated. The gene variants in CYP2C9, ABCC8/KCNJ11, and TCF7L2 were associated with the effect of sulfonylureas. CYP2C9 encodes sulfonylurea metabolizing cytochrome P450 isoenzyme 2C9, ABCC8 and KCNJ11 genes encode proteins constituting ATP-sensitive K(+) channel which is a therapeutic target for sulfonylureas, and TCF7L2 is a gene with the strongest association with type 2 diabetes. SLC22A1, SLC47A1, and ATM gene variants were repeatedly associated with the response to metformin. SLC22A1 and SLC47A1 encode metformin transporters OCT1 and MATE1, respectively. The function of a gene variant near ATM gene identified by a genome-wide association study is not elucidated so far. The first variant associated with the response to gliptins is a polymorphism in the proximity of CTRB1/2 gene which encodes chymotrypsinogen. Establishment of diabetes pharmacogenetics consortia and reduction in costs of genomics might lead to some significant clinical breakthroughs in this field in a near future.