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Cheng Y, Wang C, Zhang X, Zhao Y, Jin B, Wang C, Lu Z, Zheng F. Circulating homocysteine and folate concentrations and risk of type 2 diabetes: A retrospective observational study in Chinese adults and a Mendelian randomization analysis. Front Cardiovasc Med 2022; 9:978998. [DOI: 10.3389/fcvm.2022.978998] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/27/2022] [Accepted: 10/31/2022] [Indexed: 11/16/2022] Open
Abstract
BackgroundThe relation between circulating homocysteine (hcy) and folate concentrations and risk of type 2 diabetes mellitus (T2DM) has been evaluated in several observational studies with inconsistent results; and it is unclear about their causal relationships. Our aim was to assess the causality association between circulating hcy or folate concentrations and the development of T2DM using Mendelian randomization (MR) analysis, based on results of an observational study in Chinese adults.MethodsWe conducted an observational study of 370 patients with T2DM and 402 controls after routine physical examination who consulted at the Zhongnan Hospital of Wuhan University between March 2021 and December 2021. Correlations between hcy and folate and the incidence of T2DM were quantified using logistic regression models. Two-sample MR analysis was conducted using summary statistics of genetic variants gained from 2 genome-wide association studies (GWAS) on circulating hcy and folate concentrations in individuals of European ancestry and from an independent GWAS study based on DIAMANTE meta-analysis.ResultsIn the observational study, after logistic regression with multiple adjustment, lower hcy and higher folate levels were identified to be associated with the risk of T2DM, with OR (95% CI) for hcy of 1.032 (1.003–1.060); while 0.909 (0.840–0.983) for folate. In the MR analysis, the OR for T2DM was 1.08 (95% CI: 0.95, 1.21; P = 0.249) for each SD unit increase in genetically predicted homocysteinemia and the OR for T2DM per SD increase in genetically predicted folate elevation was 0.80 (95% CI: 0.60, 1.00, P = 0.026).ConclusionsWe discovered that high circulating hcy and low folate concentrations were related with an increased risk of developing T2DM in Chinese adults. Moreover, MR analysis provided genetic evidence for a possible causal relationship between serum folate and the risk of T2DM.
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High Folate, Perturbed One-Carbon Metabolism and Gestational Diabetes Mellitus. Nutrients 2022; 14:nu14193930. [PMID: 36235580 PMCID: PMC9573299 DOI: 10.3390/nu14193930] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/31/2022] [Revised: 09/12/2022] [Accepted: 09/20/2022] [Indexed: 11/17/2022] Open
Abstract
Folate is a dietary micronutrient essential to one-carbon metabolism. The World Health Organisation recommends folic acid (FA) supplementation pre-conception and in early pregnancy to reduce the risk of fetal neural tube defects (NTDs). Subsequently, many countries (~92) have mandatory FA fortification policies, as well as recommendations for periconceptional FA supplementation. Mandatory fortification initiatives have been largely successful in reducing the incidence of NTDs. However, humans have limited capacity to incorporate FA into the one-carbon metabolic pathway, resulting in the increasingly ubiquitous presence of circulating unmetabolised folic acid (uFA). Excess FA intake has emerged as a risk factor in gestational diabetes mellitus (GDM). Several other one-carbon metabolism components (vitamin B12, homocysteine and choline-derived betaine) are also closely entwined with GDM risk, suggesting a role for one-carbon metabolism in GDM pathogenesis. There is growing evidence from in vitro and animal studies suggesting a role for excess FA in dysregulation of one-carbon metabolism. Specifically, high levels of FA reduce methylenetetrahydrofolate reductase (MTHFR) activity, dysregulate the balance of thymidylate synthase (TS) and methionine synthase (MTR) activity, and elevate homocysteine. High homocysteine is associated with increased oxidative stress and trophoblast apoptosis and reduced human chorionic gonadotrophin (hCG) secretion and pancreatic β-cell function. While the relationship between high FA, perturbed one-carbon metabolism and GDM pathogenesis is not yet fully understood, here we summarise the current state of knowledge. Given rising rates of GDM, now estimated to be 14% globally, and widespread FA food fortification, further research is urgently needed to elucidate the mechanisms which underpin GDM pathogenesis.
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Vijayakumar A, Kim EK, Kim H, Choi YJ, Huh KB, Chang N. Effects of folic acid supplementation on serum homocysteine levels, lipid profiles, and vascular parameters in post-menopausal Korean women with type 2 diabetes mellitus. Nutr Res Pract 2017; 11:327-333. [PMID: 28765779 PMCID: PMC5537542 DOI: 10.4162/nrp.2017.11.4.327] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/10/2017] [Revised: 05/12/2017] [Accepted: 05/30/2017] [Indexed: 12/25/2022] Open
Abstract
BACKGROUND/OBJECTIVES Complications of diabetes, such as cardiovascular disease, are associated with increased mortality among type 2 diabetes mellitus patients. Homocysteine has been recently identified as a predictor of cardiovascular disease-related complications in diabetes. We investigated whether or not supplementation with folic acid tablets can lower homocysteine levels and improve parameters related with vascular complications. SUBJECTS/METHODS We conducted a non-randomized 8-week trial involving postmenopausal diabetic women (n = 25) supplemented with 800 µg of folic acid (400 µg twice a day) daily. Subjects' serum levels of folate, homocysteine, and vitamin B12 were measured, along with vascular function and brachial-ankle pulse wave velocity. RESULTS Folic acid supplementation significantly increased serum folate levels (P < 0.0001), reduced homocysteine levels (P < 0.0001), and increased vitamin B12 levels (P = 0.0063). There were significant decreases in low-density lipoprotein cholesterol levels as well as the ratios of low-density lipoprotein cholesterol to high-density lipoprotein cholesterol and total cholesterol to high-density lipoprotein cholesterol. Brachial-ankle pulse wave velocities were not altered by supplementation. Changes in serum vitamin B12 after folic acid supplementation were negatively correlated with changes in brachial-ankle pulse wave velocity. CONCLUSIONS In this study on postmenopausal Korean women with type 2 diabetes mellitus, folic acid supplementation reduced serum homocysteine levels, increased serum folate and vitamin B12 levels, and lowered lipid parameters.
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Affiliation(s)
- Aswathy Vijayakumar
- Department of Nutritional Science and Food Management, Ewha Womans University, 52, Ewhayeodae-gil, Seodaemun-gu, Seoul 03760, Korea
| | - Eun-Kyung Kim
- Department of Nutritional Science and Food Management, Ewha Womans University, 52, Ewhayeodae-gil, Seodaemun-gu, Seoul 03760, Korea
| | - Hyesook Kim
- Department of Nutritional Science and Food Management, Ewha Womans University, 52, Ewhayeodae-gil, Seodaemun-gu, Seoul 03760, Korea
| | - Young Ju Choi
- Huh's Diabetes Clinics & 21C Diabetes and Vascular Research Institute, Seoul 04101, Korea
| | - Kap Bum Huh
- Huh's Diabetes Clinics & 21C Diabetes and Vascular Research Institute, Seoul 04101, Korea
| | - Namsoo Chang
- Department of Nutritional Science and Food Management, Ewha Womans University, 52, Ewhayeodae-gil, Seodaemun-gu, Seoul 03760, Korea
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Scullion SM, Hahn C, Tyka K, Flatt PR, McClenaghan NH, Lenzen S, Gurgul-Convey E. Improved antioxidative defence protects insulin-producing cells against homocysteine toxicity. Chem Biol Interact 2016; 256:37-46. [DOI: 10.1016/j.cbi.2016.06.019] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/06/2016] [Revised: 05/16/2016] [Accepted: 06/14/2016] [Indexed: 12/31/2022]
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Patterson S, Irwin N, Guo-Parke H, Moffett RC, Scullion SM, Flatt PR, McClenaghan NH. Evaluation of the role of N-methyl-D-aspartate (NMDA) receptors in insulin secreting beta-cells. Eur J Pharmacol 2015; 771:107-13. [PMID: 26688567 DOI: 10.1016/j.ejphar.2015.12.015] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/24/2015] [Revised: 11/17/2015] [Accepted: 12/09/2015] [Indexed: 10/22/2022]
Abstract
The possibility that antagonism of N-methyl-D-aspartate (NMDA) receptors represent a novel drug target for diabetes prompted the current studies probing NMDA receptor function in the detrimental actions of homocysteine on pancreatic beta-cell function. Cellular insulin content and release, changes in membrane potential and intracellular Ca(2+) and gene expression were assessed following acute (20min) and long-term (18h) exposure of pancreatic clonal BRIN-BD11 beta-cells to known NMDA receptor modulators in the absence and presence of cytotoxic concentrations of homocysteine. As expected, acute or long-term exposure to homocysteine significantly suppressed basal and secretagogue-induced insulin release. In addition, NMDA reduced glucose-stimulated insulin secretion (GSIS). Interestingly, the selective NMDA receptor antagonist, MK-801, had no negative effects on GSIS. The effects of the NMDA receptor modulators were largely independent of effects on membrane depolarisation and increases of intracellular Ca(2+). However, combined culture of the NMDA antagonist, MK-801, with homocysteine did enhance intracellular Ca(2+) levels. Actions of NMDA agonists/antagonists and homocysteine on signal transduction pathways were independent of changes in cellular insulin content, cell viability, DNA damage or expression of key beta-cell genes. Taken together, the data support a role for NMDA receptors in controlling pancreatic beta-cell function. However, modulation of NMDA receptor function was unable to prevent the detrimental beta-cell effects of homocysteine.
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Affiliation(s)
- Steven Patterson
- SAAD Centre for Pharmacy and Diabetes, University of Ulster, Coleraine, Northern Ireland, United Kingdom
| | - Nigel Irwin
- SAAD Centre for Pharmacy and Diabetes, University of Ulster, Coleraine, Northern Ireland, United Kingdom.
| | - Hong Guo-Parke
- SAAD Centre for Pharmacy and Diabetes, University of Ulster, Coleraine, Northern Ireland, United Kingdom
| | - R Charlotte Moffett
- SAAD Centre for Pharmacy and Diabetes, University of Ulster, Coleraine, Northern Ireland, United Kingdom
| | - Siobhan M Scullion
- SAAD Centre for Pharmacy and Diabetes, University of Ulster, Coleraine, Northern Ireland, United Kingdom
| | - Peter R Flatt
- SAAD Centre for Pharmacy and Diabetes, University of Ulster, Coleraine, Northern Ireland, United Kingdom
| | - Neville H McClenaghan
- SAAD Centre for Pharmacy and Diabetes, University of Ulster, Coleraine, Northern Ireland, United Kingdom
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Scullion SM, Gurgul-Convey E, Elsner M, Lenzen S, Flatt PR, McClenaghan NH. Enhancement of homocysteine toxicity to insulin-secreting BRIN-BD11 cells in combination with alloxan. J Endocrinol 2012; 214:233-8. [PMID: 22582095 DOI: 10.1530/joe-11-0461] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
Previous studies have shown that homocysteine (HC) has a detrimental impact on insulin secretion and pancreatic beta cell function. The aim of the present study was to determine the role of reactive oxygen species (ROS) in the in vitro toxic effects of HC on insulin secretion and function of BRIN-BD11 insulin-secreting cells. In this study, insulin secretion from BRIN-BD11 cells was determined radioimmunologically, cell viability by 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl tetrazolium bromide assay and glucokinase activity by a glucose phosphorylation assay following culture with HC plus alloxan (Alx). Treatment with HC resulted in concentration-dependent inhibition of insulin secretion induced by glucose and other insulinotropic agents. HC in combination with Alx resulted in a more pronounced decline in insulin secretion, including that induced by 20 mM alanine, by 43% (P<0.001) and 30 mM KCl by 60% (P<0.001), compared with control culture. The glucokinase phosphorylating capacity in cells cultured with HC plus Alx was significantly lower, compared with control cells. The cells also displayed a significant 84% (P<0.001) decline in cell viability. Prolonged, 72-h culture of insulin-secreting cells with HC followed by 18-h culture without HC did not result in full restoration of beta cell responses to insulinotropic agents. In vitro oxygen consumption was enhanced by a combination of Alx with HC. The study arrived at the conclusion that HC generates ROS in a redox-cycling reaction with Alx that explains the decline in viability of insulin-secreting cells, leading to reduced glucokinase phosphorylating ability, diminished insulin secretory responsiveness and cell death.
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Affiliation(s)
- S M Scullion
- Diabetes Research Group, SAAD Centre for Pharmacy and Diabetes, University of Ulster, Coleraine, Northern Ireland, UK.
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Smith GC, Konycheva G, Dziadek MA, Ravelich SR, Patel S, Reddy S, Breier BH, Vickers MH, Owens JA, Ferguson LR. Pre- and postnatal methyl deficiency in the rat differentially alters glucose homeostasis. JOURNAL OF NUTRIGENETICS AND NUTRIGENOMICS 2011; 4:175-91. [PMID: 21860247 DOI: 10.1159/000330227] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/06/2011] [Accepted: 06/09/2011] [Indexed: 01/18/2023]
Abstract
BACKGROUND/AIMS Early-life methyl-donor deficiency is implicated in growth restriction and later-life development of type 2 diabetes mellitus. We ascertained whether dietary methyl-donor deficiency in the mother during pregnancy or during postweaning growth in the rat would impair glucose homeostasis, insulin secretion and pancreatic endocrine development in young adults. METHODS Effects of maternal methyl deficiency (90% deficiency in methionine, folate and choline) were compared with those of postweaning methyl deficiency and with control diets for effects on growth, impaired glucose tolerance, insulin secretion and pancreas development in offspring. Studies focussed on male offspring, which have been shown more susceptible to early-life influences on later disease development. RESULTS Prenatal methyl deficiency delayed delivery, restricted birthweight by 22%, reduced litter size by 33% and increased offspring mortality to 23% shortly after birth. It reduced relative endocrine pancreatic mass in adult male offspring to 46% of endocrine mass in controls, but only mildly impaired their glucose tolerance and insulin secretion. In contrast, postweaning methyl deficiency restricted growth of male rats and reduced relative pancreatic endocrine mass (-40%), but improved their glucose tolerance, despite decreased insulin secretion. CONCLUSION It is clear that the global undernutrition (UN) during pregnancy in rodents alters glucose metabolism in adult offspring. It has been hypothesised that alterations in epigenetic mechanisms may underlie this phenotype. However, removing all methyl donors during pregnancy, which are essential for epigenetic processes in development, did not cause any alteration in glucose metabolism in offspring as seen in the global UN model.
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Affiliation(s)
- Greg C Smith
- School of Biological Sciences, University of Auckland, Auckland, New Zealand
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Nutrient regulation of insulin secretion and beta-cell functional integrity. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2010; 654:91-114. [PMID: 20217496 DOI: 10.1007/978-90-481-3271-3_6] [Citation(s) in RCA: 51] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
Abstract
Pancreatic beta-cells are often referred to as "fuel sensors" as they continually monitor and respond to dietary nutrients, under the modulation of additional neurohormonal signals, in order to secrete insulin to best meet the needs of the organism. beta-cell nutrient sensing requires metabolic activation, resulting in production of stimulus-secretion coupling signals that promote insulin biosynthesis and release. The primary stimulus for insulin secretion is glucose, and islet beta-cells are particularly responsive to this important nutrient secretagogue, It is important to consider individual effects of different classes of nutrient or other physiological or pharmacological agents on metabolism and insulin secretion. However, given that beta-cells are continually exposed to a complex milieu of nutrients and other circulating factors, it is important to also acknowledge and examine the interplay between glucose metabolism and that of the two other primary nutrient classes, the amino acids and fatty acids. It is the mixed nutrient sensing and outputs of glucose, amino and fatty acid metabolism that generate the metabolic coupling factors (MCFs) involved in signaling for insulin exocytosis. Primary MCFs in the beta-cell include ATP, NADPH, glutamate, long chain acyl-CoA and diacylglycerol and are discussed in detail in this article.
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Cole NW, Weaver KR, Walcher BN, Adams ZF, Miller RR. Hyperglycemia-induced membrane lipid peroxidation and elevated homocysteine levels are poorly attenuated by exogenous folate in embryonic chick brains. Comp Biochem Physiol B Biochem Mol Biol 2008; 150:338-43. [DOI: 10.1016/j.cbpb.2008.04.002] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/28/2007] [Revised: 04/07/2008] [Accepted: 04/08/2008] [Indexed: 11/16/2022]
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