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Mezincescu AM, Rudd A, Cheyne L, Horgan G, Philip S, Cameron D, van Loon L, Whitfield P, Gribbin R, Hu MK, Delibegovic M, Fielding B, Lobley G, Thies F, Newby DE, Gray S, Henning A, Dawson D. Comparison of intramyocellular lipid metabolism in patients with diabetes and male athletes. Nat Commun 2024; 15:3690. [PMID: 38750012 PMCID: PMC11096352 DOI: 10.1038/s41467-024-47843-y] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/24/2023] [Accepted: 04/05/2024] [Indexed: 05/18/2024] Open
Abstract
Despite opposing insulin sensitivity and cardiometabolic risk, both athletes and patients with type 2 diabetes have increased skeletal myocyte fat storage: the so-called "athlete's paradox". In a parallel non-randomised, non-blinded trial (NCT03065140), we characterised and compared the skeletal myocyte lipid signature of 29 male endurance athletes and 30 patients with diabetes after undergoing deconditioning or endurance training respectively. The primary outcomes were to assess intramyocellular lipid storage of the vastus lateralis in both cohorts and the secondary outcomes were to examine saturated and unsaturated intramyocellular lipid pool turnover. We show that athletes have higher intramyocellular fat saturation with very high palmitate kinetics, which is attenuated by deconditioning. In contrast, type 2 diabetes patients have higher unsaturated intramyocellular fat and blunted palmitate and linoleate kinetics but after endurance training, all were realigned with those of deconditioned athletes. Improved basal insulin sensitivity was further associated with better serum cholesterol/triglycerides, glycaemic control, physical performance, enhanced post insulin receptor pathway signalling and metabolic sensing. We conclude that insulin-resistant, maladapted intramyocellular lipid storage and turnover in patients with type 2 diabetes show reversibility after endurance training through increased contributions of the saturated intramyocellular fatty acid pools. Clinical Trial Registration: NCT03065140: Muscle Fat Compartments and Turnover as Determinant of Insulin Sensitivity (MISTY).
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Affiliation(s)
- Alice M Mezincescu
- Aberdeen Cardiovascular and Diabetes Centre, University of Aberdeen, Aberdeen, UK
| | - Amelia Rudd
- Aberdeen Cardiovascular and Diabetes Centre, University of Aberdeen, Aberdeen, UK
| | - Lesley Cheyne
- Aberdeen Cardiovascular and Diabetes Centre, University of Aberdeen, Aberdeen, UK
| | | | - Sam Philip
- Aberdeen Cardiovascular and Diabetes Centre, University of Aberdeen, Aberdeen, UK
| | - Donnie Cameron
- C.J. Gorter MRI Center, Leiden University Medical Center, Leiden, The Netherlands
| | - Luc van Loon
- University of Maastricht, Maastricht, The Netherlands
| | | | | | - May Khei Hu
- Aberdeen Cardiovascular and Diabetes Centre, University of Aberdeen, Aberdeen, UK
| | - Mirela Delibegovic
- Aberdeen Cardiovascular and Diabetes Centre, University of Aberdeen, Aberdeen, UK
| | | | - Gerald Lobley
- Aberdeen Cardiovascular and Diabetes Centre, University of Aberdeen, Aberdeen, UK
| | - Frank Thies
- Aberdeen Cardiovascular and Diabetes Centre, University of Aberdeen, Aberdeen, UK
| | - David E Newby
- Centre for Cardiovascular Science, University of Edinburgh, Edinburgh, UK
| | | | | | - Dana Dawson
- Aberdeen Cardiovascular and Diabetes Centre, University of Aberdeen, Aberdeen, UK.
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Capra BT, Hudson S, Helder M, Laskaridou E, Johnson AL, Gilmore C, Marinik E, Hedrick VE, Savla J, David LA, Davy KP, Davy BM. Ultra-processed food intake, gut microbiome, and glucose homeostasis in mid-life adults: Background, design, and methods of a controlled feeding trial. Contemp Clin Trials 2024; 137:107427. [PMID: 38184104 PMCID: PMC10922925 DOI: 10.1016/j.cct.2024.107427] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/06/2023] [Revised: 12/06/2023] [Accepted: 01/01/2024] [Indexed: 01/08/2024]
Abstract
BACKGROUND Aging is associated with gut dysbiosis, low-grade inflammation, and increased risk of type 2 diabetes (T2D). Prediabetes, which increases T2D and cardiovascular disease risk, is present in 45-50% of mid-life adults. The gut microbiota may link ultra-processed food (UPF) with inflammation and T2D risk. METHODS Following a 2-week standardized lead-in diet (59% UPF), adults aged 40-65 years will be randomly assigned to a 6-week diet emphasizing either UPF (81% total energy) or non-UPF (0% total energy). Measurements of insulin sensitivity, 24-h and postprandial glycemic control, gut microbiota composition/function, fecal short chain fatty acids, intestinal inflammation, inflammatory cytokines, and vascular function will be made before and following the 6-week intervention period. Prior to recruitment, menus were developed in order to match UPF and non-UPF conditions based upon relevant dietary factors. Menus were evaluated for palatability and costs, and the commercial additive content of study diets was quantified to explore potential links with outcomes. RESULTS Overall diet palatability ratings were similar (UPF = 7.6 ± 1.0; Non-UPF = 6.8 ± 1.5; Like Moderately = 7, Like Very Much = 8). Cost analysis (food + labor) of the 2000 kcal menu (7-d average) revealed lower costs for UPF compared to non-UPF diets ($20.97/d and $40.23/d, respectively). Additive exposure assessment of the 2000 kcal UPF diet indicated that soy lecithin (16×/week), citric acid (13×/week), sorbic acid (13×/week), and sodium citrate (12×/week) were the most frequently consumed additives. CONCLUSIONS Whether UPF consumption impairs glucose homeostasis in mid-life adults is unknown. Findings will address this research gap and contribute information on how UPF consumption may influence T2D development.
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Affiliation(s)
- Bailey T Capra
- Department of Human Nutrition, Foods, and Exercise, Virginia Tech, 229 Wallace Hall, Blacksburg, VA 24061, United States of America; Virginia Tech Translational Obesity Research Interdisciplinary Graduate Education Program, United States of America.
| | - Summer Hudson
- Department of Human Nutrition, Foods, and Exercise, Virginia Tech, 229 Wallace Hall, Blacksburg, VA 24061, United States of America
| | - McKenna Helder
- Department of Food Science and Technology, Virginia Tech,United States of America
| | - Eleni Laskaridou
- Department of Human Nutrition, Foods, and Exercise, Virginia Tech, 229 Wallace Hall, Blacksburg, VA 24061, United States of America; Virginia Tech Translational Obesity Research Interdisciplinary Graduate Education Program, United States of America
| | - Aubrey L Johnson
- Department of Human Nutrition, Foods, and Exercise, Virginia Tech, 229 Wallace Hall, Blacksburg, VA 24061, United States of America; Virginia Tech Translational Obesity Research Interdisciplinary Graduate Education Program, United States of America
| | - Carson Gilmore
- Department of Human Nutrition, Foods, and Exercise, Virginia Tech, 229 Wallace Hall, Blacksburg, VA 24061, United States of America
| | - Elaina Marinik
- Department of Human Nutrition, Foods, and Exercise, Virginia Tech, 229 Wallace Hall, Blacksburg, VA 24061, United States of America; Virginia Tech Translational Obesity Research Interdisciplinary Graduate Education Program, United States of America
| | - Valisa E Hedrick
- Department of Human Nutrition, Foods, and Exercise, Virginia Tech, 229 Wallace Hall, Blacksburg, VA 24061, United States of America; Virginia Tech Translational Obesity Research Interdisciplinary Graduate Education Program, United States of America
| | - Jyoti Savla
- Virginia Tech Translational Obesity Research Interdisciplinary Graduate Education Program, United States of America; Center for Gerontology, Virginia Tech, United States of America
| | - Lawrence A David
- Department of Molecular Genetics & Microbiology, Duke University, United States of America; Duke Microbiome Center, Duke University, United States of America
| | - Kevin P Davy
- Department of Human Nutrition, Foods, and Exercise, Virginia Tech, 229 Wallace Hall, Blacksburg, VA 24061, United States of America; Virginia Tech Translational Obesity Research Interdisciplinary Graduate Education Program, United States of America
| | - Brenda M Davy
- Department of Human Nutrition, Foods, and Exercise, Virginia Tech, 229 Wallace Hall, Blacksburg, VA 24061, United States of America; Virginia Tech Translational Obesity Research Interdisciplinary Graduate Education Program, United States of America
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Barrett JS, Whytock KL, Strauss JA, Wagenmakers AJM, Shepherd SO. High intramuscular triglyceride turnover rates and the link to insulin sensitivity: influence of obesity, type 2 diabetes and physical activity. Appl Physiol Nutr Metab 2022; 47:343-356. [PMID: 35061523 DOI: 10.1139/apnm-2021-0631] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
Abstract
Large intramuscular triglyceride (IMTG) stores in sedentary, obese individuals have been linked to insulin resistance, yet well-trained athletes exhibit high IMTG levels whilst maintaining insulin sensitivity. Contrary to previous assumptions, it is now known that IMTG content per se does not result in insulin resistance. Rather, insulin resistance is caused, at least in part, by the presence of high concentrations of harmful lipid metabolites, such as diacylglycerols and ceramides in muscle. Several mechanistic differences between obese sedentary individuals and their highly trained counterparts have been identified, which determine the differential capacity for IMTG synthesis and breakdown in these populations. In this review, we first describe the most up-to-date mechanisms by which a low IMTG turnover rate (both breakdown and synthesis) leads to the accumulation of lipid metabolites and results in skeletal muscle insulin resistance. We then explore current and potential exercise and nutritional strategies that target IMTG turnover in sedentary obese individuals, to improve insulin sensitivity. Overall, improving IMTG turnover should be an important component of successful interventions that aim to prevent the development of insulin resistance in the ever-expanding sedentary, overweight and obese populations. Novelty: A description of the most up-to-date mechanisms regulating turnover of the IMTG pool. An exploration of current and potential exercise/nutritional strategies to target and enhance IMTG turnover in obese individuals. Overall, highlights the importance of improving IMTG turnover to prevent the development of insulin resistance.
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Affiliation(s)
- J S Barrett
- Research Institute for Sport & Exercise Sciences, Liverpool John Moores University, Liverpool, UK
| | - K L Whytock
- Translational Research Institute, AdventHealth, Orlando, FL 32804, USA
| | - J A Strauss
- Research Institute for Sport & Exercise Sciences, Liverpool John Moores University, Liverpool, UK
| | - A J M Wagenmakers
- Research Institute for Sport & Exercise Sciences, Liverpool John Moores University, Liverpool, UK
| | - S O Shepherd
- Research Institute for Sport & Exercise Sciences, Liverpool John Moores University, Liverpool, UK
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Broussard JL, Perreault L, Macias E, Newsom SA, Harrison K, Bui HH, Milligan P, Roth KD, Nemkov T, D’Alessandro A, Brozinick JT, Bergman BC. Sex Differences in Insulin Sensitivity are Related to Muscle Tissue Acylcarnitine But Not Subcellular Lipid Distribution. Obesity (Silver Spring) 2021; 29:550-561. [PMID: 33624435 PMCID: PMC7927726 DOI: 10.1002/oby.23106] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/14/2020] [Revised: 11/13/2020] [Accepted: 12/02/2020] [Indexed: 11/05/2022]
Abstract
OBJECTIVE Sex differences in insulin sensitivity are present throughout the life-span, with men having a higher prevalence of insulin resistance and diabetes compared with women. Differences in lean mass, fat mass, and fat distribution-particularly ectopic fat-have all been postulated to contribute to the sexual dimorphism in diabetes risk. Emerging data suggest ectopic lipid composition and subcellular localization are most relevant; however, it is not known whether they explain sex differences in obesity-induced insulin resistance. METHODS To address this gap, this study evaluated insulin sensitivity and subcellular localization of intramuscular triacylglycerol, diacylglycerol, and sphingolipids as well as muscle acylcarnitines and serum lipidomics in people with obesity. RESULTS Insulin sensitivity was significantly lower in men (P < 0.05); however, no sex differences were found in localization of intramuscular triacylglycerol, diacylglycerol, or sphingolipids in skeletal muscle. In contrast, men had higher total muscle acylcarnitine (P < 0.05) and long-chain muscle acylcarnitine (P < 0.05), which were related to lower insulin sensitivity (r = -0.42, P < 0.05). Men also displayed higher serum ceramide (P = 0.05) and lysophosphatidylcholine (P < 0.01). CONCLUSIONS These data reveal novel sex-specific associations between lipid species involved in the coupling of mitochondrial fatty acid transport, β-oxidation, and tricarboxylic acid cycle flux that may provide therapeutic targets to improve insulin sensitivity.
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Affiliation(s)
- Josiane L. Broussard
- School of Medicine, University of Colorado Anschutz Medical Campus, Aurora, Colorado, USA
- Department of Health and Exercise Science, Colorado State University, Fort Collins, Colorado, USA
| | - Leigh Perreault
- School of Medicine, University of Colorado Anschutz Medical Campus, Aurora, Colorado, USA
| | - Emily Macias
- School of Medicine, University of Colorado Anschutz Medical Campus, Aurora, Colorado, USA
| | - Sean A. Newsom
- School of Biological and Population Health Sciences, Oregon State University, Corvallis, Oregon, USA
| | - Kathleen Harrison
- School of Medicine, University of Colorado Anschutz Medical Campus, Aurora, Colorado, USA
| | | | - Paul Milligan
- North American Science Associates, Inc., Northwood, OH
| | | | - Travis Nemkov
- School of Medicine, University of Colorado Anschutz Medical Campus, Aurora, Colorado, USA
| | - Angelo D’Alessandro
- School of Medicine, University of Colorado Anschutz Medical Campus, Aurora, Colorado, USA
| | | | - Bryan C. Bergman
- School of Medicine, University of Colorado Anschutz Medical Campus, Aurora, Colorado, USA
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Kahn D, Perreault L, Macias E, Zarini S, Newsom SA, Strauss A, Kerege A, Harrison K, Snell-Bergeon J, Bergman BC. Subcellular localisation and composition of intramuscular triacylglycerol influence insulin sensitivity in humans. Diabetologia 2021; 64:168-180. [PMID: 33128577 PMCID: PMC7718332 DOI: 10.1007/s00125-020-05315-0] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/08/2020] [Accepted: 08/25/2020] [Indexed: 12/25/2022]
Abstract
AIMS/HYPOTHESIS Subcellular localisation is an important factor in the known impact of bioactive lipids, such as diacylglycerol and sphingolipids, on insulin sensitivity in skeletal muscle; yet, the role of localised intramuscular triacylglycerol (IMTG) is yet to be described. Excess accumulation of IMTG in skeletal muscle is associated with insulin resistance, and we hypothesised that differences in subcellular localisation and composition of IMTG would relate to metabolic health status in humans. METHODS We evaluated subcellular localisation of IMTG in lean participants, endurance-trained athletes, individuals with obesity and individuals with type 2 diabetes using LC-MS/MS of fractionated muscle biopsies and insulin clamps. RESULTS Insulin sensitivity was significantly different between each group (athletes>lean>obese>type 2 diabetes; p < 0.001). Sarcolemmal IMTG was significantly greater in individuals with obesity and type 2 diabetes compared with lean control participants and athletes, but individuals with type 2 diabetes were the only group with significantly increased saturated IMTG. Sarcolemmal IMTG was inversely related to insulin sensitivity. Nuclear IMTG was significantly greater in individuals with type 2 diabetes compared with lean control participants and athletes, and total and saturated IMTG localised in the nucleus had a significant inverse relationship with insulin sensitivity. Total cytosolic IMTG was not different between groups, but saturated cytosolic IMTG species were significantly increased in individuals with type 2 diabetes compared with all other groups. There were no significant differences between groups for IMTG concentration in the mitochondria/endoplasmic reticulum. CONCLUSIONS/INTERPRETATION These data reveal previously unknown differences in subcellular IMTG localisation based on metabolic health status and indicate the influence of sarcolemmal and nuclear IMTG on insulin sensitivity. Additionally, these studies suggest saturated IMTG may be uniquely deleterious for muscle insulin sensitivity. Graphical abstract.
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Affiliation(s)
- Darcy Kahn
- Division of Endocrinology, Metabolism, and Diabetes, University of Colorado Anschutz Medical Campus, Aurora, CO, USA
| | - Leigh Perreault
- Division of Endocrinology, Metabolism, and Diabetes, University of Colorado Anschutz Medical Campus, Aurora, CO, USA
| | - Emily Macias
- Division of Endocrinology, Metabolism, and Diabetes, University of Colorado Anschutz Medical Campus, Aurora, CO, USA
| | - Simona Zarini
- Division of Endocrinology, Metabolism, and Diabetes, University of Colorado Anschutz Medical Campus, Aurora, CO, USA
| | | | - Allison Strauss
- Division of Endocrinology, Metabolism, and Diabetes, University of Colorado Anschutz Medical Campus, Aurora, CO, USA
| | - Anna Kerege
- Division of Endocrinology, Metabolism, and Diabetes, University of Colorado Anschutz Medical Campus, Aurora, CO, USA
| | - Kathleen Harrison
- Division of Endocrinology, Metabolism, and Diabetes, University of Colorado Anschutz Medical Campus, Aurora, CO, USA
| | - Janet Snell-Bergeon
- Division of Endocrinology, Metabolism, and Diabetes, University of Colorado Anschutz Medical Campus, Aurora, CO, USA
| | - Bryan C Bergman
- Division of Endocrinology, Metabolism, and Diabetes, University of Colorado Anschutz Medical Campus, Aurora, CO, USA.
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Bergman BC, Goodpaster BH. Exercise and Muscle Lipid Content, Composition, and Localization: Influence on Muscle Insulin Sensitivity. Diabetes 2020; 69:848-858. [PMID: 32312901 DOI: 10.2337/dbi18-0042] [Citation(s) in RCA: 31] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/04/2019] [Accepted: 02/17/2020] [Indexed: 11/13/2022]
Abstract
Accumulation of lipid in skeletal muscle is thought to be related to the development of insulin resistance and type 2 diabetes. Initial work in this area focused on accumulation of intramuscular triglyceride; however, bioactive lipids such as diacylglycerols and sphingolipids are now thought to play an important role. Specific species of these lipids appear to be more negative toward insulin sensitivity than others. Adding another layer of complexity, localization of lipids within the cell appears to influence the relationship between these lipids and insulin sensitivity. This article summarizes how accumulation of total lipids, specific lipid species, and localization of lipids influence insulin sensitivity in humans. We then focus on how these aspects of muscle lipids are impacted by acute and chronic aerobic and resistance exercise training. By understanding how exercise alters specific species and localization of lipids, it may be possible to uncover specific lipids that most heavily impact insulin sensitivity.
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Perreault L, Newsom SA, Strauss A, Kerege A, Kahn DE, Harrison KA, Snell-Bergeon JK, Nemkov T, D'Alessandro A, Jackman MR, MacLean PS, Bergman BC. Intracellular localization of diacylglycerols and sphingolipids influences insulin sensitivity and mitochondrial function in human skeletal muscle. JCI Insight 2018; 3:96805. [PMID: 29415895 DOI: 10.1172/jci.insight.96805] [Citation(s) in RCA: 101] [Impact Index Per Article: 16.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/09/2017] [Accepted: 12/12/2017] [Indexed: 01/01/2023] Open
Abstract
BACKGROUND Accumulation of diacylglycerol (DAG) and sphingolipids is thought to promote skeletal muscle insulin resistance by altering cellular signaling specific to their location. However,the subcellular localization of bioactive lipids in human skeletal muscle is largely unknown. METHODS We evaluated subcellular localization of skeletal muscle DAGs and sphingolipids in lean individuals (n = 15), endurance-trained athletes (n = 16), and obese men and women with (n = 12) and without type 2 diabetes (n = 15). Muscle biopsies were fractionated into sarcolemmal, cytosolic, mitochondrial/ER, and nuclear compartments. Lipids were measured using liquid chromatography tandem mass spectrometry, and insulin sensitivity was measured using hyperinsulinemic-euglycemic clamp. RESULTS Sarcolemmal 1,2-DAGs were not significantly related to insulin sensitivity. Sarcolemmal ceramides were inversely related to insulin sensitivity, with a significant relationship found for the C18:0 species. Sarcolemmal sphingomyelins were also inversely related to insulin sensitivity, with the strongest relationships found for the C18:1, C18:0, and C18:2 species. In the mitochondrial/ER and nuclear fractions, 1,2-DAGs were positively related to, while ceramides were inversely related to, insulin sensitivity. Cytosolic lipids as well as 1,3-DAG, dihydroceramides, and glucosylceramides in any compartment were not related to insulin sensitivity. All sphingolipids but only specific DAGs administered to isolated mitochondria decreased mitochondrial state 3 respiration. CONCLUSION These data reveal previously unknown differences in subcellular localization of skeletal muscle DAGs and sphingolipids that relate to whole-body insulin sensitivity and mitochondrial function in humans. These data suggest that whole-cell concentrations of lipids obscure meaningful differences in compartmentalization and suggest that subcellular localization of lipids should be considered when developing therapeutic interventions to treat insulin resistance. FUNDING National Institutes of Health General Clinical Research Center (RR-00036), National Institute of Diabetes and Digestive and Kidney Diseases (NIDDK) (R01DK089170), NIDDK (T32 DK07658), and Colorado Nutrition Obesity Research Center (P30DK048520).
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Affiliation(s)
- Leigh Perreault
- Endocrinology, Diabetes, and Metabolism, School of Medicine, University of Colorado Anschutz Medical Campus, Denver, Colorado, USA
| | - Sean A Newsom
- School of Biological and Population Health Sciences, Oregon State University, Corvallis, Oregon, USA
| | - Allison Strauss
- Endocrinology, Diabetes, and Metabolism, School of Medicine, University of Colorado Anschutz Medical Campus, Denver, Colorado, USA
| | - Anna Kerege
- Endocrinology, Diabetes, and Metabolism, School of Medicine, University of Colorado Anschutz Medical Campus, Denver, Colorado, USA
| | - Darcy E Kahn
- Endocrinology, Diabetes, and Metabolism, School of Medicine, University of Colorado Anschutz Medical Campus, Denver, Colorado, USA
| | - Kathleen A Harrison
- Endocrinology, Diabetes, and Metabolism, School of Medicine, University of Colorado Anschutz Medical Campus, Denver, Colorado, USA
| | - Janet K Snell-Bergeon
- Barbara Davis Center for Childhood Diabetes, School of Medicine, University of Colorado Anschutz Medical Campus, Denver, Colorado, USA
| | - Travis Nemkov
- Department of Biochemistry and Molecular Genetics, School of Medicine, University of Colorado Anschutz Medical Campus, Denver, Colorado, USA
| | - Angelo D'Alessandro
- Department of Biochemistry and Molecular Genetics, School of Medicine, University of Colorado Anschutz Medical Campus, Denver, Colorado, USA
| | - Matthew R Jackman
- Endocrinology, Diabetes, and Metabolism, School of Medicine, University of Colorado Anschutz Medical Campus, Denver, Colorado, USA
| | - Paul S MacLean
- Endocrinology, Diabetes, and Metabolism, School of Medicine, University of Colorado Anschutz Medical Campus, Denver, Colorado, USA
| | - Bryan C Bergman
- Endocrinology, Diabetes, and Metabolism, School of Medicine, University of Colorado Anschutz Medical Campus, Denver, Colorado, USA
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Bergman BC, Perreault L, Strauss A, Bacon S, Kerege A, Harrison K, Brozinick JT, Hunerdosse DM, Playdon MC, Holmes W, Bui HH, Sanders P, Siddall P, Wei T, Thomas MK, Kuo MS, Eckel RH. Intramuscular triglyceride synthesis: importance in muscle lipid partitioning in humans. Am J Physiol Endocrinol Metab 2018; 314:E152-E164. [PMID: 28978544 PMCID: PMC5866414 DOI: 10.1152/ajpendo.00142.2017] [Citation(s) in RCA: 41] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/05/2023]
Abstract
Intramuscular triglyceride (IMTG) concentration is elevated in insulin-resistant individuals and was once thought to promote insulin resistance. However, endurance-trained athletes have equivalent concentration of IMTG compared with individuals with type 2 diabetes, and have very low risk of diabetes, termed the "athlete's paradox." We now know that IMTG synthesis is positively related to insulin sensitivity, but the exact mechanisms for this are unclear. To understand the relationship between IMTG synthesis and insulin sensitivity, we measured IMTG synthesis in obese control subjects, endurance-trained athletes, and individuals with type 2 diabetes during rest, exercise, and recovery. IMTG synthesis rates were positively related to insulin sensitivity, cytosolic accumulation of DAG, and decreased accumulation of C18:0 ceramide and glucosylceramide. Greater rates of IMTG synthesis in athletes were not explained by alterations in FFA concentration, DGAT1 mRNA expression, or protein content. IMTG synthesis during exercise in Ob and T2D indicate utilization as a fuel despite unchanged content, whereas IMTG concentration decreased during exercise in athletes. mRNA expression for genes involved in lipid desaturation and IMTG synthesis were increased after exercise and recovery. Further, in a subset of individuals, exercise decreased cytosolic and membrane di-saturated DAG content, which may help explain insulin sensitization after acute exercise. These data suggest IMTG synthesis rates may influence insulin sensitivity by altering intracellular lipid localization, and decreasing specific ceramide species that promote insulin resistance.
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Affiliation(s)
- Bryan C Bergman
- University of Colorado Anschutz Medical Campus , Aurora, Colorado
| | - Leigh Perreault
- University of Colorado Anschutz Medical Campus , Aurora, Colorado
| | - Allison Strauss
- University of Colorado Anschutz Medical Campus , Aurora, Colorado
| | - Samantha Bacon
- University of Colorado Anschutz Medical Campus , Aurora, Colorado
| | - Anna Kerege
- University of Colorado Anschutz Medical Campus , Aurora, Colorado
| | | | | | | | - Mary C Playdon
- University of Colorado Anschutz Medical Campus , Aurora, Colorado
| | | | | | | | | | - Tao Wei
- Eli Lilly, Indianapolis, Indiana
| | | | | | - Robert H Eckel
- University of Colorado Anschutz Medical Campus , Aurora, Colorado
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Blaak EE. Characterisation of fatty acid metabolism in different insulin-resistant phenotypes by means of stable isotopes. Proc Nutr Soc 2017; 76:1-7. [PMID: 28100287 DOI: 10.1017/s0029665116003013] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
Abstract
The obese insulin resistant and/or prediabetic state is characterised by systemic lipid overflow, mainly driven by an impaired lipid buffering capacity of adipose tissue, and an impaired capacity of skeletal muscle to increase fat oxidation upon increased supply. This leads to the accumulation of bioactive lipid metabolites in skeletal muscle interfering with insulin sensitivity via various mechanisms. In this review, the contribution of dietary v. endogenous fatty acids to lipid overflow, their extraction or uptake by skeletal muscle as well as the fractional synthetic rate, content and composition of the muscle lipid pools is discussed in relation to the development or presence of insulin resistance and/or an impaired glucose metabolism. These parameters are studied in vivo in man by combining a dual stable isotope methodology with [2H2]- and [U-13C]-palmitate tracers with the arterio-venous balance technique across forearm muscle and biochemical analyses in muscle biopsies. The insulin-resistant state is characterised by an elevated muscle TAG extraction, despite similar supply, and a reduced skeletal muscle lipid turnover, in particular after intake of a high fat, SFA fat meal, but not after a high fat, PUFA meal. Data are placed in the context of current literature, and underlying mechanisms and implications for long-term nutritional interventions are discussed.
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Affiliation(s)
- Ellen E Blaak
- Department of Human Biology,Maastricht University,Maastricht,The Netherlands
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10
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van der Kolk BW, Goossens GH, Jocken JW, Blaak EE. Altered skeletal muscle fatty acid handling is associated with the degree of insulin resistance in overweight and obese humans. Diabetologia 2016; 59:2686-2696. [PMID: 27627982 PMCID: PMC6518064 DOI: 10.1007/s00125-016-4104-3] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/09/2016] [Accepted: 08/12/2016] [Indexed: 01/01/2023]
Abstract
INTRODUCTION/HYPOTHESIS Disturbances in skeletal muscle fatty acid (FA) handling may contribute to the development and progression of whole-body insulin resistance (IR). In this study, we compared fasting and postprandial skeletal muscle FA handling in individuals with varying degrees of IR. METHODS Seventy-four overweight/obese participants (62 men) were divided into two groups based on the HOMA-IR median (3.35). Fasting and postprandial skeletal muscle FA handling were determined by combining the forearm muscle balance technique with stable isotopes. [2H2]palmitate was infused i.v. to label VLDL-triacylglycerol (VLDL-TAG) and NEFA in the circulation, whereas [U-13C]palmitate was incorporated in a high-saturated FA mixed-meal labelling chylomicron-TAG. Skeletal muscle biopsies were taken to assess intramuscular lipid content, fractional synthetic rate (FSR) and the transcriptional regulation of FA metabolism. RESULTS Postprandial forearm muscle VLDL-TAG extraction was elevated in the high-IR vs the mild-IR group (AUC0-4h: 0.57 ± 0.32 vs -0.43 ± 0.38 nmol [100 ml tissue]-1 min-1, respectively, p = 0.045). Although no differences in skeletal muscle TAG, diacylglycerol, NEFA content and FSR were present between groups, the high-IR group showed increased saturation of the intramuscular NEFA pool (p = 0.039). This was accompanied by lower muscle GPAT1 (also known as GPAM) expression (p = 0.050). CONCLUSIONS/INTERPRETATION Participants with high-IR demonstrated increased postprandial skeletal muscle VLDL-TAG extraction and higher saturation of the intramuscular NEFA pool vs individuals with mild-IR. These data support the involvement of disturbances in skeletal muscle FA handling in the progression of whole-body IR.
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Affiliation(s)
- Birgitta W van der Kolk
- Department of Human Biology, NUTRIM School of Nutrition and Translational Research in Metabolism, Maastricht University Medical Center+, PO Box 616, 6200 MD, Maastricht, the Netherlands.
| | - Gijs H Goossens
- Department of Human Biology, NUTRIM School of Nutrition and Translational Research in Metabolism, Maastricht University Medical Center+, PO Box 616, 6200 MD, Maastricht, the Netherlands
| | - Johan W Jocken
- Department of Human Biology, NUTRIM School of Nutrition and Translational Research in Metabolism, Maastricht University Medical Center+, PO Box 616, 6200 MD, Maastricht, the Netherlands
| | - Ellen E Blaak
- Department of Human Biology, NUTRIM School of Nutrition and Translational Research in Metabolism, Maastricht University Medical Center+, PO Box 616, 6200 MD, Maastricht, the Netherlands
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Schrauwen P, van Marken Lichtenbelt WD. Combatting type 2 diabetes by turning up the heat. Diabetologia 2016; 59:2269-2279. [PMID: 27591854 PMCID: PMC5506100 DOI: 10.1007/s00125-016-4068-3] [Citation(s) in RCA: 45] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/16/2016] [Accepted: 06/22/2016] [Indexed: 12/21/2022]
Abstract
In our westernised society, the level of physical activity is low. Interventions that increase energy expenditure are generally associated with an improvement in metabolic health. Exercise and exercise training increase energy metabolism and are considered to be among the best strategies for prevention of type 2 diabetes mellitus. More recently, cold exposure has been suggested to have a therapeutic value in type 2 diabetes. At a cellular level, there is evidence that increasing the turnover of cellular substrates such as fatty acids is associated with preventive effects against lipid-induced insulin resistance. Cellular energy sensors may underlie the effects linking energy turnover with metabolic health effects. Here we review data supporting the hypothesis that increasing energy and substrate turnover has beneficial effects on insulin sensitivity and should be considered a target for the prevention and treatment of type 2 diabetes.
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Affiliation(s)
- Patrick Schrauwen
- Department of Human Biology and Human Movement Sciences, NUTRIM School for Nutrition and Translational Research in Metabolism, Maastricht University Medical Center, P.O. BOX 616, 6200MD, Maastricht, the Netherlands.
| | - Wouter D van Marken Lichtenbelt
- Department of Human Biology and Human Movement Sciences, NUTRIM School for Nutrition and Translational Research in Metabolism, Maastricht University Medical Center, P.O. BOX 616, 6200MD, Maastricht, the Netherlands
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12
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The Flexibility of Ectopic Lipids. Int J Mol Sci 2016; 17:ijms17091554. [PMID: 27649157 PMCID: PMC5037826 DOI: 10.3390/ijms17091554] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/26/2016] [Revised: 08/30/2016] [Accepted: 09/01/2016] [Indexed: 02/07/2023] Open
Abstract
In addition to the subcutaneous and the visceral fat tissue, lipids can also be stored in non-adipose tissue such as in hepatocytes (intrahepatocellular lipids; IHCL), skeletal (intramyocellular lipids; IMCL) or cardiac muscle cells (intracardiomyocellular lipids; ICCL). Ectopic lipids are flexible fuel stores that can be depleted by physical exercise and repleted by diet. They are related to obesity and insulin resistance. Quantification of IMCL was initially performed invasively, using muscle biopsies with biochemical and/or histological analysis. 1H-magnetic resonance spectroscopy (1H-MRS) is now a validated method that allows for not only quantifying IMCL non-invasively and repeatedly, but also assessing IHCL and ICCL. This review summarizes the current available knowledge on the flexibility of ectopic lipids. The available evidence suggests a complex interplay between quantitative and qualitative diet, fat availability (fat mass), insulin action, and physical exercise, all important factors that influence the flexibility of ectopic lipids. Furthermore, the time frame of the intervention on these parameters (short-term vs. long-term) appears to be critical. Consequently, standardization of physical activity and diet are critical when assessing ectopic lipids in predefined clinical situations.
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13
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Newsom SA, Brozinick JT, Kiseljak-Vassiliades K, Strauss AN, Bacon SD, Kerege AA, Bui HH, Sanders P, Siddall P, Wei T, Thomas M, Kuo MS, Nemkov T, D'Alessandro A, Hansen KC, Perreault L, Bergman BC. Skeletal muscle phosphatidylcholine and phosphatidylethanolamine are related to insulin sensitivity and respond to acute exercise in humans. J Appl Physiol (1985) 2016; 120:1355-63. [PMID: 27032901 DOI: 10.1152/japplphysiol.00664.2015] [Citation(s) in RCA: 47] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/06/2015] [Accepted: 03/30/2016] [Indexed: 01/05/2023] Open
Abstract
Several recent reports indicate that the balance of skeletal muscle phosphatidylcholine (PC) and phosphatidylethanolamine (PE) is a key determinant of muscle contractile function and metabolism. The purpose of this study was to determine relationships between skeletal muscle PC, PE and insulin sensitivity, and whether PC and PE are dynamically regulated in response to acute exercise in humans. Insulin sensitivity was measured via intravenous glucose tolerance in sedentary obese adults (OB; n = 14), individuals with type 2 diabetes (T2D; n = 15), and endurance-trained athletes (ATH; n = 15). Vastus lateralis muscle biopsies were obtained at rest, immediately after 90 min of cycle ergometry at 50% maximal oxygen consumption (V̇o2 max), and 2-h postexercise (recovery). Skeletal muscle PC and PE were measured via infusion-based mass spectrometry/mass spectrometry analysis. ATH had greater levels of muscle PC and PE compared with OB and T2D (P < 0.05), with total PC and PE positively relating to insulin sensitivity (both P < 0.05). Skeletal muscle PC:PE ratio was elevated in T2D compared with OB and ATH (P < 0.05), tended to be elevated in OB vs. ATH (P = 0.07), and was inversely related to insulin sensitivity among the entire cohort (r = -0.43, P = 0.01). Muscle PC and PE were altered by exercise, particularly after 2 h of recovery, in a highly group-specific manner. However, muscle PC:PE ratio remained unchanged in all groups. In summary, total muscle PC and PE are positively related to insulin sensitivity while PC:PE ratio is inversely related to insulin sensitivity in humans. A single session of exercise significantly alters skeletal muscle PC and PE levels, but not PC:PE ratio.
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Affiliation(s)
- Sean A Newsom
- Division of Endocrinology, Metabolism and Diabetes, University of Colorado Anschutz Medical Campus, Aurora, Colorado
| | | | - Katja Kiseljak-Vassiliades
- Division of Endocrinology, Metabolism and Diabetes, University of Colorado Anschutz Medical Campus, Aurora, Colorado
| | - Allison N Strauss
- Division of Endocrinology, Metabolism and Diabetes, University of Colorado Anschutz Medical Campus, Aurora, Colorado
| | - Samantha D Bacon
- Division of Endocrinology, Metabolism and Diabetes, University of Colorado Anschutz Medical Campus, Aurora, Colorado
| | - Anna A Kerege
- Division of Endocrinology, Metabolism and Diabetes, University of Colorado Anschutz Medical Campus, Aurora, Colorado
| | | | - Phil Sanders
- Eli Lilly and Company, Indianapolis, Indiana; and
| | | | - Tao Wei
- Eli Lilly and Company, Indianapolis, Indiana; and
| | | | | | - Travis Nemkov
- Department of Biochemistry and Molecular Genetics, University of Colorado Anschutz Medical Campus, Aurora, Colorado
| | - Angelo D'Alessandro
- Department of Biochemistry and Molecular Genetics, University of Colorado Anschutz Medical Campus, Aurora, Colorado
| | - Kirk C Hansen
- Department of Biochemistry and Molecular Genetics, University of Colorado Anschutz Medical Campus, Aurora, Colorado
| | - Leigh Perreault
- Division of Endocrinology, Metabolism and Diabetes, University of Colorado Anschutz Medical Campus, Aurora, Colorado
| | - Bryan C Bergman
- Division of Endocrinology, Metabolism and Diabetes, University of Colorado Anschutz Medical Campus, Aurora, Colorado;
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14
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Altered Skeletal Muscle Fatty Acid Handling in Subjects with Impaired Glucose Tolerance as Compared to Impaired Fasting Glucose. Nutrients 2016; 8:164. [PMID: 26985905 PMCID: PMC4808892 DOI: 10.3390/nu8030164] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/12/2016] [Revised: 02/24/2016] [Accepted: 03/09/2016] [Indexed: 12/11/2022] Open
Abstract
Altered skeletal muscle fatty acid (FA) metabolism contributes to insulin resistance. Here, we compared skeletal muscle FA handling between subjects with impaired fasting glucose (IFG; n = 12 (7 males)) and impaired glucose tolerance (IGT; n = 14 (7 males)) by measuring arterio-venous concentration differences across forearm muscle. [²H₂]-palmitate was infused intravenously, labeling circulating endogenous triacylglycerol (TAG) and free fatty acids (FFA), whereas [U-(13)C]-palmitate was incorporated in a high-fat mixed-meal, labeling chylomicron-TAG. Skeletal muscle biopsies were taken to determine muscle TAG, diacylglycerol (DAG), FFA, and phospholipid content, their fractional synthetic rate (FSR) and degree of saturation, and gene expression. Insulin sensitivity was assessed using a hyperinsulinemic-euglycemic clamp. Net skeletal muscle glucose uptake was lower (p = 0.018) and peripheral insulin sensitivity tended to be reduced (p = 0.064) in IGT as compared to IFG subjects. Furthermore, IGT showed higher skeletal muscle extraction of VLDL-TAG (p = 0.043), higher muscle TAG content (p = 0.025), higher saturation of FFA (p = 0.004), lower saturation of TAG (p = 0.017) and a tendency towards a lower TAG FSR (p = 0.073) and a lower saturation of DAG (p = 0.059) versus IFG individuals. Muscle oxidative gene expression was lower in IGT subjects. In conclusion, increased liver-derived TAG extraction and reduced lipid turnover of saturated FA, rather than DAG content, in skeletal muscle accompany the more pronounced insulin resistance in IGT versus IFG subjects.
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15
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Stinkens R, Goossens GH, Jocken JWE, Blaak EE. Targeting fatty acid metabolism to improve glucose metabolism. Obes Rev 2015; 16:715-57. [PMID: 26179344 DOI: 10.1111/obr.12298] [Citation(s) in RCA: 100] [Impact Index Per Article: 11.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/02/2015] [Revised: 04/23/2015] [Accepted: 05/10/2015] [Indexed: 12/15/2022]
Abstract
Disturbances in fatty acid metabolism in adipose tissue, liver, skeletal muscle, gut and pancreas play an important role in the development of insulin resistance, impaired glucose metabolism and type 2 diabetes mellitus. Alterations in diet composition may contribute to prevent and/or reverse these disturbances through modulation of fatty acid metabolism. Besides an increased fat mass, adipose tissue dysfunction, characterized by an altered capacity to store lipids and an altered secretion of adipokines, may result in lipid overflow, systemic inflammation and excessive lipid accumulation in non-adipose tissues like liver, skeletal muscle and the pancreas. These impairments together promote the development of impaired glucose metabolism, insulin resistance and type 2 diabetes mellitus. Furthermore, intrinsic functional impairments in either of these organs may contribute to lipotoxicity and insulin resistance. The present review provides an overview of fatty acid metabolism-related pathways in adipose tissue, liver, skeletal muscle, pancreas and gut, which can be targeted by diet or food components, thereby improving glucose metabolism.
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Affiliation(s)
- R Stinkens
- Department of Human Biology, NUTRIM School of Nutrition and Translational Research in Metabolism, Maastricht University Medical Center+, Maastricht, The Netherlands
| | - G H Goossens
- Department of Human Biology, NUTRIM School of Nutrition and Translational Research in Metabolism, Maastricht University Medical Center+, Maastricht, The Netherlands
| | - J W E Jocken
- Department of Human Biology, NUTRIM School of Nutrition and Translational Research in Metabolism, Maastricht University Medical Center+, Maastricht, The Netherlands
| | - E E Blaak
- Department of Human Biology, NUTRIM School of Nutrition and Translational Research in Metabolism, Maastricht University Medical Center+, Maastricht, The Netherlands
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16
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Bays H. Central obesity as a clinical marker of adiposopathy; increased visceral adiposity as a surrogate marker for global fat dysfunction. Curr Opin Endocrinol Diabetes Obes 2014; 21:345-51. [PMID: 25106000 PMCID: PMC4154790 DOI: 10.1097/med.0000000000000093] [Citation(s) in RCA: 92] [Impact Index Per Article: 9.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Abstract
PURPOSE OF REVIEW Subcutaneous adipose tissue (SAT) is often described as 'protective'. Visceral adipose tissue (VAT) is often described as 'pathologic'. However, both SAT and VAT have protective and pathologic potential, with interdependent biologic functions. RECENT FINDINGS Most of the body's (excess) energy is stored as fat in SAT. If during positive caloric balance, SAT does not undergo adequate adipogenesis, then excess energy may result in adipocyte hypertrophy, leading to hypoxia, immunopathies, and endocrinopathies. Energy overflow may promote accumulation of pericardial fat, perivascular fat, and myocardial fat, which may directly contribute to atherosclerotic cardiovascular disease (CVD). Lipotoxic free fatty acid delivery to nonadipose body organs (e.g. liver, muscle, and pancreas) may indirectly contribute to CVD by promoting the most common metabolic disorders encountered in clinical practice (e.g. high blood sugars, high blood pressure, and dyslipidaemia), all major CVD risk factors. Finally, SAT energy overflow may increase VAT accumulation, which is also associated with increased risk of metabolic diseases and CVD. SUMMARY Increased VAT is a surrogate marker for SAT dysfunction which increases waist circumference, reflecting a shared pathologic process leading to the pathogenic fat accumulation of other fat depots and fatty infiltration of nonadipose body organs. Central obesity is a clinical marker for adiposopathy.
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Affiliation(s)
- Harold Bays
- Louisville Metabolic and Atherosclerosis Research Center, Louisville, Kentucky, USA
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17
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Abstract
Among lean populations, cardiovascular disease (CVD) is rare. Among those with increased adiposity, CVD is the commonest cause of worldwide death. The "obesity paradox" describes seemingly contrary relationships between body fat and health/ill-health. Multiple obesity paradoxes exist, and include the anatomic obesity paradox, physiologic obesity paradox, demographic obesity paradox, therapeutic obesity paradox, cardiovascular event/procedure obesity paradox, and obesity treatment paradox. Adiposopathy ("sick fat") is defined as adipocyte/adipose tissue dysfunction caused by positive caloric balance and sedentary lifestyle in genetically and environmentally susceptible individuals. Adiposopathy contributes to the commonest metabolic disorders encountered in clinical practice (high glucose levels, high blood pressure, dyslipidemia, etc.), all major CVD risk factors. Ockham's razor is a principle of parsimony which postulates that among competing theories, the hypothesis with the fewest assumptions is the one best selected. Ockham's razor supports adiposopathy as the primary cause of most cases of adiposity-related metabolic diseases, which in turn helps resolve the obesity paradox.
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Affiliation(s)
- Harold Bays
- Louisville Metabolic and Atherosclerosis Research Center, 3288 Illinois Avenue, Louisville, KY, 40213, USA,
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18
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Perreault L, Færch K. Approaching pre-diabetes. J Diabetes Complications 2014; 28:226-33. [PMID: 24342268 DOI: 10.1016/j.jdiacomp.2013.10.008] [Citation(s) in RCA: 42] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/12/2013] [Revised: 10/18/2013] [Accepted: 10/19/2013] [Indexed: 01/06/2023]
Abstract
As the global epidemic of type 2 diabetes continues to rise, the time has come to revisit our approach to pre-diabetes. Recently, much ado has been made about screening, diagnosis, pathophysiology and clinical interventions in pre-diabetes, and all for good reason as the key to reversing the diabetes epidemic likely lies therein. The somewhat controversial term "pre-diabetes" represents collective dysglycemic states intermediate between normal glucose regulation (NGR) and diabetes. Not all people with pre-diabetes will develop diabetes, but the majority will. In fact, up to 70% of those with pre-diabetes may acquire the disease over their lifetime. Furthermore, even when overt diabetes is delayed or prevented, both micro- and macrovascular disease appears more prevalent in those with pre-diabetes compared to their normoglycemic peers. Hence, there is growing consensus that NGR should be the goal for people with pre-diabetes. Nevertheless, there is much to consider in that pursuit. Herein, we provide an update on the global burden of pre-diabetes, its underlying pathophysiology and discuss clinical considerations in these individuals at high risk of developing diabetes.
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Affiliation(s)
- Leigh Perreault
- University of Colorado Anschutz Medical Center, Aurora, CO, USA.
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19
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Goyal SN, Haiderali S, Reddy M N, Arya DS, Patil CR. Prediabetes: grounds of pitfall signalling alteration for cardiovascular disease. RSC Adv 2014. [DOI: 10.1039/c4ra10366a] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022] Open
Abstract
Prediabetes manifested by impaired glucose tolerance and impaired fasting glucose offers high risk of myocardial dysfunction by causing endothelial dysfunction, inflammation, oxidative stress, atherosclerosis and genetic alterations.
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Affiliation(s)
- Sameer N. Goyal
- Cardiovascular Pharmacology Division
- Department of Pharmacology
- R. C. Patel Institute of Pharmaceutical Education and Research
- Dhule, India
| | - Shaikh Haiderali
- Cardiovascular Pharmacology Division
- Department of Pharmacology
- R. C. Patel Institute of Pharmaceutical Education and Research
- Dhule, India
| | - Navya Reddy M
- Cardiovascular Pharmacology Division
- Department of Pharmacology
- R. C. Patel Institute of Pharmaceutical Education and Research
- Dhule, India
| | - Dharamvir Singh Arya
- Department of Pharmacology
- All India Institute of Medical Sciences
- New Delhi-110029, India
| | - Chandragouda R. Patil
- Cardiovascular Pharmacology Division
- Department of Pharmacology
- R. C. Patel Institute of Pharmaceutical Education and Research
- Dhule, India
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20
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Stephens FB, Wall BT, Marimuthu K, Shannon CE, Constantin-Teodosiu D, Macdonald IA, Greenhaff PL. Skeletal muscle carnitine loading increases energy expenditure, modulates fuel metabolism gene networks and prevents body fat accumulation in humans. J Physiol 2013; 591:4655-66. [PMID: 23818692 DOI: 10.1113/jphysiol.2013.255364] [Citation(s) in RCA: 49] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022] Open
Abstract
Twelve weeks of daily l-carnitine and carbohydrate feeding in humans increases skeletal muscle total carnitine content, and prevents body mass accrual associated with carbohydrate feeding alone. Here we determined the influence of L-carnitine and carbohydrate feeding on energy metabolism, body fat mass and muscle expression of fuel metabolism genes. Twelve males exercised at 50% maximal oxygen consumption for 30 min once before and once after 12 weeks of twice daily feeding of 80 g carbohydrate (Control, n=6) or 1.36 g L-carnitine + 80 g carbohydrate (Carnitine, n=6). Maximal carnitine palmitolytransferase 1 (CPT1) activity remained similar in both groups over 12 weeks. However, whereas muscle total carnitine, long-chain acyl-CoA and whole-body energy expenditure did not change over 12 weeks in Control, they increased in Carnitine by 20%, 200% and 6%, respectively (P<0.05). Moreover, body mass and whole-body fat mass (dual-energy X-ray absorptiometry) increased over 12 weeks in Control by 1.9 and 1.8 kg, respectively (P<0.05), but did not change in Carnitine. Seventy-three of 187 genes relating to fuel metabolism were upregulated in Carnitine vs. Control after 12 weeks, with 'insulin signalling', 'peroxisome proliferator-activated receptor signalling' and 'fatty acid metabolism' as the three most enriched pathways in gene functional analysis. In conclusion, increasing muscle total carnitine in healthy humans can modulate muscle metabolism, energy expenditure and body composition over a prolonged period, which is entirely consistent with a carnitine-mediated increase in muscle long-chain acyl-group translocation via CPT1. Implications to health warrant further investigation, particularly in obese individuals who have a reduced reliance on muscle fat oxidation during low-intensity exercise.
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Affiliation(s)
- Francis B Stephens
- Professor P. Greenhaff: MRC/Arthritis Research UK Centre for Musculoskeletal Ageing Research, School of Biomedical Sciences, University of Nottingham Medical School, Queen's Medical Centre, Nottingham NG7 2UH, UK.
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21
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Malin SK, Viskochil R, Oliver C, Braun B. Mild fasting hyperglycemia shifts fuel reliance toward fat during exercise in adults with impaired glucose tolerance. J Appl Physiol (1985) 2013; 115:78-83. [PMID: 23599396 DOI: 10.1152/japplphysiol.00084.2013] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Impaired glucose tolerance (IGT) is characterized by decreased oxidative capacity and reduced carbohydrate utilization during exercise. However, it is unclear if the presence of impaired fasting glucose (IFG) affects fuel utilization during exercise in adults with IGT. We tested the hypothesis that the presence of IFG in adults with IGT decreases reliance on carbohydrate during exercise. Middle-aged, obese, sedentary individuals (n = 6, IGT and n = 6, IFG+IGT) were compared during exercise at 60% peak O2 consumption for 45 min on a cycle ergometer. Glucose rates of appearance and disposal and muscle glycogen were assessed by stable isotope dilution methods, and fat utilization was estimated via indirect calorimetry. A 75-g oral glucose tolerance test was used to determine fasting and 2-h glucose concentrations. A glucose intolerance severity z-score was calculated from the oral glucose tolerance test. Glucose flux (i.e., rates of appearance and disposal) was not different between groups. However, individuals with IFG+IGT had lower muscle glycogen use (P < 0.05) and elevated fat oxidation (P < 0.01) during exercise compared with those with isolated IGT. Plasma nonesterified fatty acids and glucose were significantly higher during exercise in subjects with IFG+IGT vs. IGT alone (P < 0.05). Fat utilization during exercise correlated with fasting glucose (r = 0.57, P = 0.05), glucose intolerance severity z-score (r = 0.66, P = 0.01), and nonesterified fatty acids (trend; r = 0.55, P = 0.08). The presence of IFG shifts fuel selection toward increased fat oxidation and decreased muscle glycogen utilization during exercise in adults with IGT. Whether these differences in substrate use contribute to, or are the result of, movement along the continuum from prediabetes to type 2 diabetes awaits further work.
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Affiliation(s)
- Steven K Malin
- Energy Metabolism Laboratory, Department of Kinesiology, University of Massachusetts, Amherst, MA 01003, USA
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22
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Beaudry JL, Riddell MC. Effects of glucocorticoids and exercise on pancreatic β-cell function and diabetes development. Diabetes Metab Res Rev 2012; 28:560-73. [PMID: 22556149 DOI: 10.1002/dmrr.2310] [Citation(s) in RCA: 57] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
Abstract
Peripheral insulin resistance and pancreatic β-cell dysfunction are hallmark characteristics of type 2 diabetes mellitus (T2DM). Several contributing factors have been proposed to promote these two defects in individuals with T2DM, including physical inactivity and chronic exposure to various psychosocial factors that increase the body's exposure to glucocorticoids, the main stress hormones in humans. Initially, β-cells have been shown to adapt to these stimuli, a phenomenon known as β-cell 'compensation'. However, long-term exposure to these physiologic and psychological stressors induces islet failure. Interestingly, glucocorticoids stimulate β-cell mass growth in parallel with promoting severe insulin resistance, the former being an important adaptive response to the latter. The direct relationship between glucocorticoids and β-cell dysfunction remains a controversial area of research. Elevations in circulating and/or tissue specific glucocorticoids have been associated with the development of obesity and T2DM in human and rodent models; however, the progression from insulin resistance to overt T2DM is highly disputed with respect to the in vivo and in vitro effects of glucocorticoids. Paradoxically, both intermittent physical stress and regular exercise alleviate insulin resistance and help to preserve β-cell mass, potentially by lowering glucocorticoid levels. Recent studies have begun to examine the mechanisms of intermittent and chronic glucocorticoid exposure and regular exercise in altering β-cell function. This review highlights recent discoveries on the physiological regulation of β-cells and diabetes development in conditions of elevated glucocorticoids, regular exercise and intermittent stress.
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Affiliation(s)
- Jacqueline L Beaudry
- School of Kinesiology and Health Science, York University, North York, Ontario, Canada
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Berings M, Wehlou C, Verrijken A, Deschepper E, Mertens I, Kaufman JM, Van Gaal LF, Ouwens DM, Ruige JB. Glucose intolerance and the amount of visceral adipose tissue contribute to an increase in circulating triglyceride concentrations in Caucasian obese females. PLoS One 2012; 7:e45145. [PMID: 23028811 PMCID: PMC3460993 DOI: 10.1371/journal.pone.0045145] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/05/2012] [Accepted: 08/13/2012] [Indexed: 01/05/2023] Open
Abstract
Context Lipotoxicity is a risk factor for developing obesity-related metabolic complications, including non-alcoholic fatty liver disease, type 2 diabetes (DM2), cardiovascular disease and stroke. Yet, the mechanisms underlying the development of lipotoxicity itself remain poorly understood. Here, we investigated whether glucose intolerance aggravates lipotoxicity by evaluating the association between triglyceride (TG) concentrations and glucose tolerance status in a cross-sectional study on obese Caucasian women at risk for DM2. Methods 913 obese females unknown to have diabetes were recruited (mean age: 41.2±SD 12.3; median BMI: 36.2, IQR 32.9–40.2). Visceral (VAT) and subcutaneous abdominal adipose tissue volumes were quantified with computed tomography. Glucose, insulin, and triglyceride concentrations were determined in fasting state and following a 75 gram oral glucose tolerance test. Results Based on fasting and 2 h post-load glucose levels, 27% of the women had impaired glucose tolerance (IGT), and 8% had newly diagnosed DM2. Fasting TG concentrations were similar between the IGT- and DM2-groups, and increased as compared to women with normal glucose tolerance (NGT). Even when adjusting for age, hip circumference and VAT, fasting TG concentrations remained elevated as compared to NGT. Mixed modelling analysis of post-load responses showed that TG concentrations declined more slowly in the DM2-group as compared to IGT and NGT. However, when adjusting for VAT the difference in decline between the glucose tolerance groups disappeared. Conclusions Glucose intolerance associates with elevated fasting TG concentrations in obese Caucasian women. We propose that glucose intolerance and increased VAT reduce lipid disposal mechanisms and may accelerate lipotoxicity.
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Affiliation(s)
- Margot Berings
- Department of Endocrinology, Ghent University Hospital, Ghent, Belgium
| | - Charline Wehlou
- Department of Endocrinology, Ghent University Hospital, Ghent, Belgium
| | - An Verrijken
- Department of Endocrinology, Diabetology and Metabolism, Antwerp University Hospital, Antwerp, Belgium
| | | | - Ilse Mertens
- Department of Endocrinology, Diabetology and Metabolism, Antwerp University Hospital, Antwerp, Belgium
| | - Jean-Marc Kaufman
- Department of Endocrinology, Ghent University Hospital, Ghent, Belgium
| | - Luc F. Van Gaal
- Department of Endocrinology, Diabetology and Metabolism, Antwerp University Hospital, Antwerp, Belgium
| | - D. Margriet Ouwens
- German Diabetes Center, Institute for Clinical Biochemistry and Pathobiochemistry, Düsseldorf, Germany
| | - Johannes B. Ruige
- Department of Endocrinology, Ghent University Hospital, Ghent, Belgium
- * E-mail:
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24
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Jans A, Konings E, Goossens GH, Bouwman FG, Moors CC, Boekschoten MV, Afman LA, Müller M, Mariman EC, Blaak EE. PUFAs acutely affect triacylglycerol-derived skeletal muscle fatty acid uptake and increase postprandial insulin sensitivity. Am J Clin Nutr 2012; 95:825-36. [PMID: 22338035 DOI: 10.3945/ajcn.111.028787] [Citation(s) in RCA: 43] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022] Open
Abstract
BACKGROUND Dietary fat quality may influence skeletal muscle lipid processing and fat accumulation, thereby modulating insulin sensitivity. OBJECTIVE The objective was to examine the acute effects of meals with various fatty acid (FA) compositions on skeletal muscle FA processing and postprandial insulin sensitivity in obese, insulin-resistant men. DESIGN In a single-blind, randomized, crossover study, 10 insulin-resistant men consumed 3 high-fat mixed meals (2.6 MJ), which were high in SFAs, MUFAs, or PUFAs. Fasting and postprandial skeletal muscle FA processing was examined by measuring differences in arteriovenous concentrations across the forearm muscle. [²H₂]Palmitate was infused intravenously to label endogenous triacylglycerol and FFAs in the circulation, and [U-¹³C]palmitate was added to the meal to label chylomicron-triacylglycerol. Skeletal muscle biopsy samples were taken to assess intramuscular lipid metabolism and gene expression. RESULTS Insulin and glucose responses (AUC) after the SFA meal were significantly higher than those after the PUFA meal (P = 0.006 and 0.033, respectively). Uptake of triacylglycerol-derived FAs was lower in the postprandial phase after the PUFA meal than after the other meals (AUC₆₀₋₂₄₀; P = 0.02). The fractional synthetic rate of the triacylglycerol, diacylglycerol, and phospholipid pool was higher after the MUFA meal than after the SFA meal. PUFA induced less transcriptional downregulation of oxidative pathways than did the other meals. CONCLUSION PUFAs reduced triacylglycerol-derived skeletal muscle FA uptake, which was accompanied by higher postprandial insulin sensitivity, a more transcriptional oxidative phenotype, and altered intramyocellular lipid partitioning and may therefore be protective against the development of insulin resistance.
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Affiliation(s)
- Anneke Jans
- Department of Human Biology, NUTRIM School for Nutrition, Toxicology and Metabolism, Maastricht University Medical Centre, Maastricht, Netherlands
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Re-evaluating lipotoxic triggers in skeletal muscle: Relating intramyocellular lipid metabolism to insulin sensitivity. Prog Lipid Res 2012; 51:36-49. [DOI: 10.1016/j.plipres.2011.11.003] [Citation(s) in RCA: 97] [Impact Index Per Article: 8.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
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Jonkers RAM, Geraedts TR, van Loon LJC, Nicolay K, Prompers JJ. Multitissue assessment of in vivo postprandial intracellular lipid partitioning in rats using localized 1H-[13C] magnetic resonance spectroscopy. Magn Reson Med 2011; 68:997-1006. [PMID: 22213012 DOI: 10.1002/mrm.23321] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/18/2011] [Revised: 11/17/2011] [Accepted: 11/17/2011] [Indexed: 12/24/2022]
Abstract
Excess accumulation of lipids in nonadipose tissues such as skeletal muscle and liver has been implicated in the development of obesity-related disorders, but the cause of this ectopic lipid overload remains unknown. The aim of this study was to determine in vivo postprandial lipid partitioning in rat skeletal muscle and liver, using localized 1H-[13C] magnetic resonance spectroscopy in combination with the oral administration of 13C-labeled lipids. Six rats were measured at baseline and 5 and 24 h after administration of 400 mg [U-13C]-labeled algal lipids. Five hours after administration, fractional 13C enrichments of the lipid pools in muscle and liver were increased 3.9-fold and 4.6-fold (P<0.05), respectively, indicating that part of the ingested lipids had been taken up by muscle and liver tissue. At 24 h, fractional 13C enrichments of muscle and liver lipids were decreased 1.6-fold and 2.2-fold (P<0.05), respectively, compared with the 5 h values. This can be interpreted as a depletion of 13C-labeled lipids from the intracellular lipid pools as a consequence of lipid turnover. In conclusion, the novel application of 1H-[13C] magnetic resonance spectroscopy in combination with the oral administration of 13C-labeled lipids is applicable for the longitudinal assessment of in vivo lipid partitioning between multiple tissues.
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Affiliation(s)
- Richard A M Jonkers
- Biomedical NMR, Department of Biomedical Engineering, Eindhoven University of Technology, Eindhoven, The Netherlands
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Mittendorfer B. Origins of metabolic complications in obesity: adipose tissue and free fatty acid trafficking. Curr Opin Clin Nutr Metab Care 2011; 14:535-41. [PMID: 21849896 PMCID: PMC3711689 DOI: 10.1097/mco.0b013e32834ad8b6] [Citation(s) in RCA: 87] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
PURPOSE OF REVIEW Obesity is associated with a number of serious medical complications that are risk factors for cardiovascular disease (e.g., insulin resistance, dyslipidemia, and liver fat accumulation). Alterations in fatty acid trafficking, both between tissues and within cells, represent a key feature in the pathophysiology of the metabolic complications in obese patients. The ways by which fatty acid 're-routing' may affect metabolic function are summarized in this article. RECENT FINDINGS Ectopic fat accumulation (i.e., fat accumulation in nonadipose tissues) appears to be a key feature distinguishing metabolically healthy from metabolically abnormal patients. This observation has led to the belief that an imbalance in fatty acid trafficking away from adipose tissue toward nonadipose tissues is a primary cause for the development of metabolic alterations in obese patients. More recently, however, it has become apparent that fatty acid trafficking within nonadipose tissues cells (i.e., toward storage - in the form of triglycerides - and oxidation) may be equally important in determining a person's risk for development of metabolic disease. SUMMARY The pathophysiology of the metabolic alterations associated with obesity is probably multifactorial within a complex network of coordinated physiological responses. Only through the integration of multiple concepts, will it be possible to further our understanding in this area and to help prevent the metabolic alterations associated with obesity.
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Affiliation(s)
- Bettina Mittendorfer
- Division of Geriatrics and Nutritional Sciences, Washington University School of Medicine, St. Louis, Missouri, USA.
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Shaw CS, Cooper NM, Shaw O, Salomao P, Wagenmakers AJM. Acute high-fat feeding does not prevent the improvement in glucose tolerance after resistance exercise in lean individuals. Eur J Appl Physiol 2011; 111:2607-13. [PMID: 21380544 DOI: 10.1007/s00421-011-1872-9] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/19/2010] [Accepted: 02/11/2011] [Indexed: 12/13/2022]
Abstract
Our first aim was to investigate whether the ingestion of a single high-fat meal impairs glucose tolerance. Our second aim was to investigate whether improvements in glucose tolerance that are seen after resistance exercise remain when exercise is performed after ingestion of a high-fat meal. Eight young males consumed either a high fat (HF) or an isocaloric control (CON) meal in the morning and underwent an oral glucose tolerance test (OGTT) 6 h later. On two other occasions, a single 1 h bout of resistance exercise was completed 2 h after consumption of each meal (HFE and CONE). There were no significant differences in plasma glucose and plasma insulin areas under the curve (AUC) or estimates of insulin sensitivity between the HF and CON trials (P > 0.05). The HFE and CONE trials elicited a ~20% lower plasma glucose AUC (P < 0.05) compared to their respective control trials. The HFE also elicited a ~25% lower plasma insulin AUC (P < 0.05) in comparison to the HF trial. The HFE trial also significantly improved estimates of insulin sensitivity in comparison to the HF condition (P < 0.05). In conclusion, this study demonstrates that consumption of a single HF meal does not impair glucose tolerance in the resting state in lean individuals and that an acute bout of resistance exercise remains effective in enhancing glucose tolerance following the ingestion of a single high-fat meal.
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Affiliation(s)
- Christopher S Shaw
- Exercise Metabolism Research Group, School of Sport and Exercise Sciences, University of Birmingham, Edgbaston, Birmingham, United Kingdom.
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Perreault L, Bergman BC, Hunerdosse DM, Eckel RH. Altered intramuscular lipid metabolism relates to diminished insulin action in men, but not women, in progression to diabetes. Obesity (Silver Spring) 2010; 18:2093-100. [PMID: 20379150 PMCID: PMC3230250 DOI: 10.1038/oby.2010.76] [Citation(s) in RCA: 39] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/12/2023]
Abstract
Whether sex differences in intramuscular triglyceride (IMTG) metabolism underlie sex differences in the progression to diabetes are unknown. Therefore, the current study examined IMTG concentration and fractional synthesis rate (FSR) in obese men and women with normal glucose tolerance (NGT) vs. those with prediabetes (PD). PD (n = 13 men and 7 women) and NGT (n = 7 men and 12 women) groups were matched for age and anthropometry. Insulin action was quantified using a hyperinsulinemic-euglycemic clamp with infusion of [6,6-(2)H(2)]-glucose. IMTG concentration was measured by gas chromatography/mass spectrometry (GC/MS) and FSR by GC/combustion isotope ratio MS (C-IRMS), from muscle biopsies taken after infusion of [U-(13)C]palmitate during 4 h of rest. In PD men, the metabolic clearance rate (MCR) of glucose was lower during the clamp (4.71 ± 0.77 vs. 8.62 ± 1.26 ml/kg fat-free mass (FFM)/min, P = 0.04; with a trend for lower glucose rate of disappearance (Rd), P = 0.07), in addition to higher IMTG concentration (41.2 ± 5.0 vs. 21.2 ± 3.4 µg/mg dry weight, P ≤ 0.01), lower FSR (0.21 ± 0.03 vs. 0.42 ± 0.06 %/h, P ≤ 0.01), and lower oxidative capacity (P = 0.03) compared to NGT men. In contrast, no difference in Rd, IMTG concentration, or FSR was seen in PD vs. NGT women. Surprisingly, glucose Rd during the clamp was not different between NGT men and women (P = 0.25) despite IMTG concentration being higher (42.6 ± 6.1 vs. 21.2 ± 3.4 µg/mg dry weight, P = 0.03) and FSR being lower (0.23 ± 0.04 vs. 0.42 ± 0.06 %/h, P = 0.02) in women. Alterations in IMTG metabolism relate to diminished insulin action in men, but not women, in the progression toward diabetes.
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Affiliation(s)
- Leigh Perreault
- Division of Endocrinology, Metabolism and Diabetes, Department of Medicine, University of Colorado Denver School of Medicine, Aurora, Colorado, USA.
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