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Gonzalez JT, Lolli L, Veasey RC, Rumbold PLS, Betts JA, Atkinson G, Stevenson EJ. Are there interindividual differences in the reactive hypoglycaemia response to breakfast? A replicate crossover trial. Eur J Nutr 2024; 63:2897-2909. [PMID: 39231870 PMCID: PMC11519142 DOI: 10.1007/s00394-024-03467-y] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/21/2024] [Accepted: 07/01/2024] [Indexed: 09/06/2024]
Abstract
BACKGROUND Following consumption of a meal, circulating glucose concentrations can rise and then fall briefly below the basal/fasting concentrations. This phenomenon is known as reactive hypoglycaemia but to date no researcher has explored potential inter-individual differences in response to meal consumption. OBJECTIVE We conducted a secondary analysis of existing data to examine inter-individual variability of reactive hypoglycaemia in response to breakfast consumption. METHODS Using a replicate crossover design, 12 healthy, physically active men (age: 18-30 y, body mass index: 22.1 to 28.0 kg⋅m- 2) completed two identical control (continued overnight fasting) and two breakfast (444 kcal; 60% carbohydrate, 17% protein, 23% fat) conditions in randomised sequences. Blood glucose and lactate concentrations, serum insulin and non-esterified fatty acid concentrations, whole-body energy expenditure, carbohydrate and fat oxidation rates, and appetite ratings were determined before and 2 h after the interventions. Inter-individual differences were explored using Pearson's product-moment correlations between the first and second replicates of the fasting-adjusted breakfast response. Within-participant covariate-adjusted linear mixed models and a random-effects meta-analytical approach were used to quantify participant-by-condition interactions. RESULTS Breakfast consumption lowered 2-h blood glucose by 0.44 mmol/L (95%CI: 0.76 to 0.12 mmol/L) and serum NEFA concentrations, whilst increasing blood lactate and serum insulin concentrations (all p < 0.01). Large, positive correlations were observed between the first and second replicates of the fasting-adjusted insulin, lactate, hunger, and satisfaction responses to breakfast consumption (all r > 0.5, 90%CI ranged from 0.03 to 0.91). The participant-by-condition interaction response variability (SD) for serum insulin concentration was 11 pmol/L (95%CI: 5 to 16 pmol/L), which was consistent with the τ-statistic from the random-effects meta-analysis (11.7 pmol/L, 95%CI 7.0 to 22.2 pmol/L) whereas effects were unclear for other outcome variables (e.g., τ-statistic value for glucose: 0 mmol/L, 95%CI 0.0 to 0.5 mmol/L). CONCLUSIONS Despite observing reactive hypoglycaemia at the group level, we were unable to detect any meaningful inter-individual variability of the reactive hypoglycaemia response to breakfast. There was, however, evidence that 2-h insulin responses to breakfast display meaningful inter-individual variability, which may be explained by relative carbohydrate dose ingested and variation in insulin sensitivity of participants.
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Affiliation(s)
- Javier T Gonzalez
- Centre for Nutrition, Exercise and Metabolism, University of Bath, Bath, UK.
- Department for Health, University of Bath, Bath, BA2 7AY, UK.
| | - Lorenzo Lolli
- Department of Sport and Exercise Sciences, Institute of Sport, Manchester Metropolitan University, Manchester, UK
| | - Rachel C Veasey
- Department of Sport, Exercise and Rehabilitation, Faculty of Health and Life Sciences, Northumbria University, Newcastle Upon Tyne, UK
| | - Penny L S Rumbold
- Department of Sport, Exercise and Rehabilitation, Faculty of Health and Life Sciences, Northumbria University, Newcastle Upon Tyne, UK
| | - James A Betts
- Centre for Nutrition, Exercise and Metabolism, University of Bath, Bath, UK
- Department for Health, University of Bath, Bath, BA2 7AY, UK
| | - Greg Atkinson
- School of Sport and Exercise Sciences, Liverpool John Moores University, Liverpool, UK
| | - Emma J Stevenson
- Faculty of Medical Sciences, Human Nutrition Research Centre, Population Health Sciences Institute, Newcastle University, Newcastle upon Tyne, UK
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Waterman HL, Moore MC, Smith MS, Farmer B, Scott M, Edgerton DS, Cherrington AD. Duration of morning hyperinsulinemia determines hepatic glucose uptake and glycogen storage later in the day. Am J Physiol Endocrinol Metab 2024; 327:E655-E667. [PMID: 39259163 PMCID: PMC11559653 DOI: 10.1152/ajpendo.00170.2024] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/07/2024] [Revised: 08/20/2024] [Accepted: 09/06/2024] [Indexed: 09/12/2024]
Abstract
The second-meal phenomenon refers to the improvement in glucose tolerance seen following a second identical meal. We previously showed that 4 h of morning hyperinsulinemia, but not hyperglycemia, enhanced hepatic glucose uptake (HGU) and glycogen storage during an afternoon hyperinsulinemic-hyperglycemic (HIHG) clamp. Our current aim was to determine if the duration or pattern of morning hyperinsulinemia is important for the afternoon response to a HIHG clamp. To determine this, the same total amount of insulin was administered either over 2 h in the first (Ins2h-A) or second (Ins2h-B) half of the morning or over the entire 4 h (Ins4h) of the morning. In the 4-h afternoon period, all three groups had 4x-basal insulin, 2x-basal glycemia, and portal glucose infusion to expose the liver to the primary postprandial regulators of hepatic glucose metabolism. During the afternoon clamp, there was a marked increase in HGU and hepatic glycogen synthesis in the Ins4h group compared with the Ins2h-A and Ins2h-B groups, despite matched hepatic glucose loads and total insulin infusion rates. Thus, the longer duration (Ins4h) of lower hyperinsulinemia in the morning seems to be the key to much greater liver glucose uptake during the afternoon clamp.NEW & NOTEWORTHY Morning insulin exposure primes the liver for increased hepatic glucose uptake and glycogen storage during a subsequent hyperinsulinemic-hyperglycemic clamp. This study addressed whether the pattern and/or duration of insulin delivery in the morning influences insulin's ensuing priming effect. We found that despite receiving equal total doses of insulin in the morning, a prolonged, lower rate of morning insulin delivery improved afternoon liver glucose metabolism more effectively than a shorter, higher rate of delivery.
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Affiliation(s)
- Hannah L Waterman
- Department of Molecular Physiology & Biophysics, Vanderbilt University School of Medicine, Nashville, Tennessee, United States
| | - Mary Courtney Moore
- Department of Molecular Physiology & Biophysics, Vanderbilt University School of Medicine, Nashville, Tennessee, United States
| | - Marta S Smith
- Department of Molecular Physiology & Biophysics, Vanderbilt University School of Medicine, Nashville, Tennessee, United States
| | - Ben Farmer
- Department of Molecular Physiology & Biophysics, Vanderbilt University School of Medicine, Nashville, Tennessee, United States
| | - Melanie Scott
- Department of Molecular Physiology & Biophysics, Vanderbilt University School of Medicine, Nashville, Tennessee, United States
| | - Dale S Edgerton
- Department of Molecular Physiology & Biophysics, Vanderbilt University School of Medicine, Nashville, Tennessee, United States
| | - Alan D Cherrington
- Department of Molecular Physiology & Biophysics, Vanderbilt University School of Medicine, Nashville, Tennessee, United States
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Waterman HL, Moore MC, Smith MS, Farmer B, Yankey K, Scott M, Edgerton DS, Cherrington AD. Morning Engagement of Hepatic Insulin Receptors Improves Afternoon Hepatic Glucose Disposal and Storage. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2024:2024.09.25.614969. [PMID: 39386695 PMCID: PMC11463395 DOI: 10.1101/2024.09.25.614969] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/12/2024]
Abstract
Glucose tolerance improves significantly upon consuming a second, identical meal later in the day (second meal phenomenon). We previously established that morning hyperinsulinemia primes the liver for increased afternoon hepatic glucose uptake (HGU). Although the route of insulin delivery is an important determinant of the mechanisms by which insulin regulates liver glucose metabolism (direct hepatic vs indirect insulin action), it is not known if insulin's delivery route affects the second meal response. To determine whether morning peripheral insulin delivery (as occurs clinically (subcutaneous)) can enhance afternoon HGU, conscious dogs were treated in the morning with insulin delivered via the portal vein, or peripherally (leg vein), while glucose was infused to maintain euglycemia. Consequently, arterial insulin levels increased similarly in both groups, but relative hepatic insulin deficiency occurred when insulin was delivered peripherally. In the afternoon, all animals were challenged with the same hyperinsulinemic-hyperglycemic clamp to simulate identical postprandial-like conditions. The substantial enhancement of HGU in the afternoon caused by morning portal vein insulin delivery was lost when insulin was delivered peripherally. This indicates that morning insulin does not cause the second meal phenomenon via its indirect actions on the liver, but rather through direct activation of hepatic insulin signaling.
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Affiliation(s)
- Hannah L Waterman
- Department of Molecular Physiology & Biophysics, Vanderbilt University School of Medicine
| | - Mary Courtney Moore
- Department of Molecular Physiology & Biophysics, Vanderbilt University School of Medicine
| | - Marta S Smith
- Department of Molecular Physiology & Biophysics, Vanderbilt University School of Medicine
| | - Ben Farmer
- Department of Molecular Physiology & Biophysics, Vanderbilt University School of Medicine
| | - Kalisha Yankey
- Department of Molecular Physiology & Biophysics, Vanderbilt University School of Medicine
| | - Melanie Scott
- Department of Molecular Physiology & Biophysics, Vanderbilt University School of Medicine
| | - Dale S Edgerton
- Department of Molecular Physiology & Biophysics, Vanderbilt University School of Medicine
| | - Alan D Cherrington
- Department of Molecular Physiology & Biophysics, Vanderbilt University School of Medicine
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Waterman HL, Moore MC, Smith MS, Farmer B, Scott M, Edgerton DS, Cherrington AD. Duration of Morning Hyperinsulinemia Determines Hepatic Glucose Uptake and Glycogen Storage Later in the Day. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2024:2024.05.10.593551. [PMID: 38798653 PMCID: PMC11118521 DOI: 10.1101/2024.05.10.593551] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/29/2024]
Abstract
The second meal phenomenon refers to the improvement in glucose tolerance seen following a second identical meal. We previously showed that 4 hours of morning hyperinsulinemia, but not hyperglycemia, enhanced hepatic glucose uptake (HGU) and glycogen storage during an afternoon hyperinsulinemic-hyperglycemic (HIHG) clamp. Our current aim was to determine if the duration or pattern of morning hyperinsulinemia is important for the afternoon response to a HIHG clamp. To determine this, we administered the same total amount of insulin either over 2h in the first (Ins2h-A) or second (Ins2h-B) half of the morning, or over the entire 4h (Ins4h) of the morning. In the 4h afternoon period, all three groups had 4x-basal insulin, 2x-basal glycemia, and portal glucose infusion to expose the liver to the primary postprandial regulators of hepatic glucose metabolism. During the afternoon clamp, there was a marked increase in HGU and hepatic glycogen synthesis in the Ins4h group compared to the Ins2h-A and Ins2h-B groups, despite matched hepatic glucose loads and total insulin infusion rates. Thus, the longer duration (Ins4h) of lower hyperinsulinemia in the morning seems to be the key to much greater liver glucose uptake during the afternoon clamp.
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Affiliation(s)
- Hannah L Waterman
- Department of Molecular Physiology & Biophysics, Vanderbilt University School of Medicine
| | - Mary Courtney Moore
- Department of Molecular Physiology & Biophysics, Vanderbilt University School of Medicine
| | - Marta S Smith
- Department of Molecular Physiology & Biophysics, Vanderbilt University School of Medicine
| | - Ben Farmer
- Department of Molecular Physiology & Biophysics, Vanderbilt University School of Medicine
| | - Melanie Scott
- Department of Molecular Physiology & Biophysics, Vanderbilt University School of Medicine
| | - Dale S Edgerton
- Department of Molecular Physiology & Biophysics, Vanderbilt University School of Medicine
| | - Alan D Cherrington
- Department of Molecular Physiology & Biophysics, Vanderbilt University School of Medicine
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Smith HA, Watkins JD, Walhin JP, Gonzalez JT, Thompson D, Betts JA. Whey Protein-Enriched and Carbohydrate-Rich Breakfasts Attenuate Insulinemic Responses to an ad libitum Lunch Relative to Extended Morning Fasting: A Randomized Crossover Trial. J Nutr 2023; 153:2842-2853. [PMID: 37557957 PMCID: PMC10613723 DOI: 10.1016/j.tjnut.2023.08.008] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/12/2022] [Revised: 07/24/2023] [Accepted: 08/04/2023] [Indexed: 08/11/2023] Open
Abstract
BACKGROUND Typical breakfast foods are rich in carbohydrate, so they not only elevate blood glucose during the morning, but also elicit a second-meal effect that can attenuate blood glucose responses in the afternoon. OBJECTIVES To determine whether a reduced-carbohydrate protein-enriched breakfast can elicit similar effects on glucose control later in the day but without hyperglycemia in the morning. METHODS In a randomized crossover design, 12 healthy men and women (age 22 ± 2 y, BMI 24.1 ± 3.6 kg·m-2; Mean ± SD) completed 3 experimental conditions. In all conditions, participants consumed an ad libitum lunch at 1200 ± 1 h but differed in terms of whether they had fasted all morning (control) or had consumed a standardized porridge breakfast at 0900 ± 1 h (320 ± 50 kcal; prescribed relative to resting metabolic rate) that was either carbohydrate-rich (50 ± 10 g CHO) or protein-enriched (that is, isoenergetic substitution of carbohydrate for 15 g whey protein isolate). RESULTS The protein-enriched breakfast reduced the morning glycemic response (iAUC 87 ± 36 mmol·L-1·180 min) relative to the carbohydrate-rich breakfast (119 ± 37 mmol·L-1·180 min; P = 0.03). Despite similar energy intake at lunch in all 3 conditions (protein-enriched 769 ± 278 kcal; carbohydrate-rich 753 ± 223 kcal; fasting 790 ± 227 kcal), postlunch insulinemic responses were markedly attenuated when breakfasts had been consumed that were either protein-enriched (18.0 ± 8.0 nmol·L-1·120 min; P = 0.05) or carbohydrate-rich (16.0 ± 7.7 nmol·L-1·120 min; P = 0.005), relative to when lunch was consumed in an overnight fasted state (26.9 ± 13.5 nmol·L-1·120 min). CONCLUSIONS Breakfast consumption attenuates insulinemic responses to a subsequent meal, achieved with consumption of energy-matched breakfasts typically high in carbohydrates or enriched with whey protein isolate relative to extended morning fasting. TRIAL REGISTRATION NUMBER NCT03866720 (clinicaltrials.gov).
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Affiliation(s)
- Harry A Smith
- Centre for Nutrition, Exercise and Metabolism, Department for Health, University of Bath, Bath, United Kingdom
| | - Jonathan D Watkins
- Centre for Nutrition, Exercise and Metabolism, Department for Health, University of Bath, Bath, United Kingdom
| | - Jean-Philippe Walhin
- Centre for Nutrition, Exercise and Metabolism, Department for Health, University of Bath, Bath, United Kingdom
| | - Javier T Gonzalez
- Centre for Nutrition, Exercise and Metabolism, Department for Health, University of Bath, Bath, United Kingdom
| | - Dylan Thompson
- Centre for Nutrition, Exercise and Metabolism, Department for Health, University of Bath, Bath, United Kingdom
| | - James A Betts
- Centre for Nutrition, Exercise and Metabolism, Department for Health, University of Bath, Bath, United Kingdom.
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Edinburgh RM, Hengist A, Smith HA, Travers RL, Koumanov F, Betts JA, Thompson D, Walhin JP, Wallis GA, Hamilton DL, Stevenson EJ, Tipton KD, Gonzalez JT. Preexercise breakfast ingestion versus extended overnight fasting increases postprandial glucose flux after exercise in healthy men. Am J Physiol Endocrinol Metab 2018; 315:E1062-E1074. [PMID: 30106621 PMCID: PMC6293167 DOI: 10.1152/ajpendo.00163.2018] [Citation(s) in RCA: 32] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
The aim of this study was to characterize postprandial glucose flux after exercise in the fed versus overnight fasted state and to investigate the potential underlying mechanisms. In a randomized order, twelve men underwent breakfast-rest [(BR) 3 h semirecumbent], breakfast-exercise [(BE) 2 h semirecumbent before 60 min of cycling (50% peak power output)], and overnight fasted exercise [(FE) as per BE omitting breakfast] trials. An oral glucose tolerance test (OGTT) was completed after exercise (after rest on BR). Dual stable isotope tracers ([U-13C] glucose ingestion and [6,6-2H2] glucose infusion) and muscle biopsies were combined to assess postprandial plasma glucose kinetics and intramuscular signaling, respectively. Plasma intestinal fatty acid binding (I-FABP) concentrations were determined as a marker of intestinal damage. Breakfast before exercise increased postexercise plasma glucose disposal rates during the OGTT, from 44 g/120 min in FE {35 to 53 g/120 min [mean (normalized 95% confidence interval)] to 73 g/120 min in BE [55 to 90 g/120 min; P = 0.01]}. This higher plasma glucose disposal rate was, however, offset by increased plasma glucose appearance rates (principally OGTT-derived), resulting in a glycemic response that did not differ between BE and FE ( P = 0.11). Plasma I-FABP concentrations during exercise were 264 pg/ml (196 to 332 pg/ml) lower in BE versus FE ( P = 0.01). Breakfast before exercise increases postexercise postprandial plasma glucose disposal, which is offset (primarily) by increased appearance rates of orally ingested glucose. Therefore, metabolic responses to fed-state exercise cannot be readily inferred from studies conducted in a fasted state.
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Affiliation(s)
| | - Aaron Hengist
- Department for Health, University of Bath , Bath , United Kingdom
| | - Harry A Smith
- Department for Health, University of Bath , Bath , United Kingdom
| | | | | | - James A Betts
- Department for Health, University of Bath , Bath , United Kingdom
| | - Dylan Thompson
- Department for Health, University of Bath , Bath , United Kingdom
| | | | - Gareth A Wallis
- School of Sport, Exercise and Rehabilitation, University of Birmingham , Birmingham , United Kingdom
| | - D Lee Hamilton
- Physiology, Exercise and Nutrition Research Group, University of Stirling, Stirling, United Kingdom
- School of Exercise and Nutrition Sciences, Deakin University, Victoria , Australia
| | - Emma J Stevenson
- Human Nutrition Research Centre, Institute of Cellular Medicine, Newcastle University , Newcastle-upon-Tyne , United Kingdom
| | - Kevin D Tipton
- Physiology, Exercise and Nutrition Research Group, University of Stirling, Stirling, United Kingdom
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Moore MC, Smith MS, Farmer B, Coate KC, Kraft G, Shiota M, Williams PE, Cherrington AD. Morning Hyperinsulinemia Primes the Liver for Glucose Uptake and Glycogen Storage Later in the Day. Diabetes 2018; 67:1237-1245. [PMID: 29666062 PMCID: PMC6014555 DOI: 10.2337/db17-0979] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/15/2017] [Accepted: 04/10/2018] [Indexed: 12/13/2022]
Abstract
We observed that a 4-h morning (AM) duodenal infusion of glucose versus saline doubled hepatic glucose uptake (HGU) and storage during a hyperinsulinemic-hyperglycemic (HIHG) clamp that afternoon (PM). To separate the effects of AM hyperglycemia versus AM hyperinsulinemia on the PM response, we used hepatic balance and tracer ([3-3H]glucose) techniques in conscious dogs. From 0 to 240 min, dogs underwent a euinsulinemic-hyperglycemic (GLC; n = 7) or hyperinsulinemic-euglycemic (INS; n = 8) clamp. Tracer equilibration and basal sampling occurred from 240 to 360 min, followed by an HIHG clamp (360-600 min; four times basal insulin, two times basal glycemia) with portal glucose infusion (4 mg ⋅ kg-1 ⋅ min-1). In the HIHG clamp, HGU (5.8 ± 0.9 vs. 3.3 ± 0.3 mg ⋅ kg-1 ⋅ min-1) and net glycogen storage (6.0 ± 0.8 vs. 2.9 ± 0.5 mg ⋅ kg-1 ⋅ min-1) were approximately twofold greater in INS than in GLC. PM hepatic glycogen content (1.9 ± 0.2 vs. 1.3 ± 0.2 g/kg body weight) and glycogen synthase (GS) activity were also greater in INS versus GLC, whereas glycogen phosphorylase (GP) activity was reduced. Thus AM hyperinsulinemia, but not AM hyperglycemia, enhanced the HGU response to a PM HIHG clamp by augmenting GS and reducing GP activity. AM hyperinsulinemia can prime the liver to extract and store glucose more effectively during subsequent same-day meals, potentially providing a tool to improve glucose control.
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Affiliation(s)
- Mary Courtney Moore
- Department of Molecular Physiology and Biophysics, Vanderbilt University School of Medicine, Nashville, TN
- Diabetes Research and Training Center, Vanderbilt University School of Medicine, Nashville, TN
| | - Marta S Smith
- Department of Molecular Physiology and Biophysics, Vanderbilt University School of Medicine, Nashville, TN
| | - Ben Farmer
- Department of Molecular Physiology and Biophysics, Vanderbilt University School of Medicine, Nashville, TN
- Diabetes Research and Training Center, Vanderbilt University School of Medicine, Nashville, TN
| | - Katie C Coate
- Department of Nutrition and Dietetics, Samford University, Birmingham, AL
| | - Guillaume Kraft
- Department of Molecular Physiology and Biophysics, Vanderbilt University School of Medicine, Nashville, TN
| | - Masakazu Shiota
- Department of Molecular Physiology and Biophysics, Vanderbilt University School of Medicine, Nashville, TN
- Diabetes Research and Training Center, Vanderbilt University School of Medicine, Nashville, TN
| | - Phillip E Williams
- Diabetes Research and Training Center, Vanderbilt University School of Medicine, Nashville, TN
- Department of Surgery, Vanderbilt University School of Medicine, Nashville, TN
| | - Alan D Cherrington
- Department of Molecular Physiology and Biophysics, Vanderbilt University School of Medicine, Nashville, TN
- Diabetes Research and Training Center, Vanderbilt University School of Medicine, Nashville, TN
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Small L, Brandon AE, Turner N, Cooney GJ. Modeling insulin resistance in rodents by alterations in diet: what have high-fat and high-calorie diets revealed? Am J Physiol Endocrinol Metab 2018; 314:E251-E265. [PMID: 29118016 DOI: 10.1152/ajpendo.00337.2017] [Citation(s) in RCA: 35] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/25/2022]
Abstract
For over half a century, researchers have been feeding different diets to rodents to examine the effects of macronutrients on whole body and tissue insulin action. During this period, the number of different diets and the source of macronutrients employed have grown dramatically. Because of the large heterogeneity in both the source and percentage of different macronutrients used for studies, it is not surprising that different high-calorie diets do not produce the same changes in insulin action. Despite this, diverse high-calorie diets continue to be employed in an attempt to generate a "generic" insulin resistance. The high-fat diet in particular varies greatly between studies with regard to the source, complexity, and ratio of dietary fat, carbohydrate, and protein. This review examines the range of rodent dietary models and methods for assessing insulin action. In almost all studies reviewed, rodents fed diets that had more than 45% of dietary energy as fat or simple carbohydrates had reduced whole body insulin action compared with chow. However, different high-calorie diets produced significantly different effects in liver, muscle, and whole body insulin action when insulin action was measured by the hyperinsulinemic-euglycemic clamp method. Rodent dietary models remain an important tool for exploring potential mechanisms of insulin resistance, but more attention needs to be given to the total macronutrient content and composition when interpreting dietary effects on insulin action.
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Affiliation(s)
- Lewin Small
- Diabetes and Metabolism Division, Garvan Institute , Sydney, New South Wales , Australia
| | - Amanda E Brandon
- Diabetes and Metabolism Division, Garvan Institute , Sydney, New South Wales , Australia
- Sydney Medical School, Charles Perkins Centre, The University of Sydney , New South Wales , Australia
| | - Nigel Turner
- Department of Pharmacology, School of Medical Science, University of New South Wales , Sydney, New South Wales , Australia
| | - Gregory J Cooney
- Diabetes and Metabolism Division, Garvan Institute , Sydney, New South Wales , Australia
- Sydney Medical School, Charles Perkins Centre, The University of Sydney , New South Wales , Australia
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