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Małkowska P. Positive Effects of Physical Activity on Insulin Signaling. Curr Issues Mol Biol 2024; 46:5467-5487. [PMID: 38920999 PMCID: PMC11202552 DOI: 10.3390/cimb46060327] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/23/2024] [Revised: 05/24/2024] [Accepted: 05/28/2024] [Indexed: 06/27/2024] Open
Abstract
Physical activity is integral to metabolic health, particularly in addressing insulin resistance and related disorders such as type 2 diabetes mellitus (T2DM). Studies consistently demonstrate a strong association between physical activity levels and insulin sensitivity. Regular exercise interventions were shown to significantly improve glycemic control, highlighting exercise as a recommended therapeutic strategy for reducing insulin resistance. Physical inactivity is closely linked to islet cell insufficiency, exacerbating insulin resistance through various pathways including ER stress, mitochondrial dysfunction, oxidative stress, and inflammation. Conversely, physical training and exercise preserve and restore islet function, enhancing peripheral insulin sensitivity. Exercise interventions stimulate β-cell proliferation through increased circulating levels of growth factors, further emphasizing its role in maintaining pancreatic health and glucose metabolism. Furthermore, sedentary lifestyles contribute to elevated oxidative stress levels and ceramide production, impairing insulin signaling and glucose metabolism. Regular exercise induces anti-inflammatory responses, enhances antioxidant defenses, and promotes mitochondrial function, thereby improving insulin sensitivity and metabolic efficiency. Encouraging individuals to adopt active lifestyles and engage in regular exercise is crucial for preventing and managing insulin resistance and related metabolic disorders, ultimately promoting overall health and well-being.
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Affiliation(s)
- Paulina Małkowska
- Institute of Physical Culture Sciences, University of Szczecin, 71-065 Szczecin, Poland
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Vazquez Rocha L, Macdonald I, Alssema M, Færch K. The Use and Effectiveness of Selected Alternative Markers for Insulin Sensitivity and Secretion Compared with Gold Standard Markers in Dietary Intervention Studies in Individuals without Diabetes: Results of a Systematic Review. Nutrients 2022; 14:nu14102036. [PMID: 35631177 PMCID: PMC9143618 DOI: 10.3390/nu14102036] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/03/2022] [Revised: 05/02/2022] [Accepted: 05/10/2022] [Indexed: 12/10/2022] Open
Abstract
Background: The gold-standard techniques for measuring insulin sensitivity and secretion are well established. However, they may be perceived as invasive and expensive for use in dietary intervention studies. Thus, surrogate markers have been proposed as alternative markers for insulin sensitivity and secretion. This systematic review aimed to identify markers of insulin sensitivity and secretion in response to dietary intervention and assess their suitability as surrogates for the gold-standard methodology. Methods: Three databases, PubMed, Scopus, and Cochrane were searched, intervention studies and randomised controlled trials reporting data on dietary intake, a gold standard of analysis of insulin sensitivity (either euglycaemic-hyperinsulinaemic clamp or intravenous glucose tolerance test and secretion (acute insulin response to glucose), as well as surrogate markers for insulin sensitivity (either fasting insulin, area under the curve oral glucose tolerance tests and HOMA-IR) and insulin secretion (disposition index), were selected. Results: We identified thirty-five studies that were eligible for inclusion. We found insufficient evidence to predict insulin sensitivity and secretion with surrogate markers when compared to gold standards in nutritional intervention studies. Conclusions: Future research is needed to investigate if surrogate measures of insulin sensitivity and secretion can be repeatable and reproducible in the same way as gold standards.
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Affiliation(s)
- Lucia Vazquez Rocha
- School of Biosciences, University of Nottingham, Loughborough LE12 5RD, UK
- Correspondence:
| | - Ian Macdonald
- School of Life Sciences, University of Nottingham, Nottingham NG7 2UH, UK;
- Nestle Institute of Health Sciences, 1015 Lausanne, Switzerland
| | - Marjan Alssema
- Unilever Research and Development, 3133 AT Vlaardingen, The Netherlands;
| | - Kristine Færch
- Steno Diabetes Center Copenhagen, 2730 Herlev, Denmark;
- Department of Biomedical Sciences, University of Copenhagen, 2200 Copenhagen, Denmark
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Bartlette K, Carreau AM, Xie D, Garcia-Reyes Y, Rahat H, Pyle L, Nadeau KJ, Cree-Green M, Diniz Behn C. Oral minimal model-based estimates of insulin sensitivity in obese youth depend on oral glucose tolerance test protocol duration. Metabol Open 2021; 9:100078. [PMID: 33511337 PMCID: PMC7817496 DOI: 10.1016/j.metop.2021.100078] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/30/2020] [Revised: 01/01/2021] [Accepted: 01/02/2021] [Indexed: 12/17/2022] Open
Abstract
Introduction The Oral Minimal Model (OMM), a differential-equations based mathematical model of glucose-insulin dynamics, utilizes data from a frequently sampled oral glucose tolerance test (OGTT) to quantify insulin sensitivity ( S I ). OMM-based estimates of S I can detect differences in insulin resistance (IR) across population groups and quantify effects of clinical or behavioral interventions. These estimates of S I have been validated in healthy adults using data from OGTTs with durations from 2 to 7 h. However, data demonstrating how protocol duration affects S I estimates in highly IR populations such as adolescents with obesity are limited. Methods A 6-h frequently sampled OGTT was performed in adolescent females with obesity. Two, 3-, and 4- hour implementations of OMM assuming an exponentially-decaying rate of glucose appearance beyond measured glucose concentrations were compared to the 6-h implementation. A 4- hour OMM implementation with truncated data (4h Tr) was also considered. Results Data from 68 participants were included (age 15.8 ± 1.2 years, BMI 35.4 ± 5.6 kg/m2). Although S I values were highly correlated for all implementations, they varied with protocol duration (2h: 2.86 ± 3.31, 3h: 2.55 ± 2.62, 4h: 2.81 ± 2.59, 4h tr: 3.13 ± 3.14, 6h: 3.06 ± 2.85 x 10-4 dl/kg/min per U/ml). S I estimates based on 2 or 3 h of data underestimated S I values, whereas 4-h S I estimates more closely approximated 6-h S I values. Discussion These results suggest that OGTT protocol duration should be considered when implementing OMM to estimate S I in adolescents with obesity and other IR populations.
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Affiliation(s)
- Kai Bartlette
- Department of Applied Mathematics and Statistics, Colorado School of Mines, Golden, CO, 80401, USA
| | - Anne-Marie Carreau
- Division of Endocrinology, Department of Pediatrics, University of Colorado Denver Anschutz Medical Campus, Aurora, CO, 80045, USA
| | - Danielle Xie
- Division of Endocrinology, Department of Pediatrics, University of Colorado Denver Anschutz Medical Campus, Aurora, CO, 80045, USA
| | - Yesenia Garcia-Reyes
- Division of Endocrinology, Department of Pediatrics, University of Colorado Denver Anschutz Medical Campus, Aurora, CO, 80045, USA
| | - Haseeb Rahat
- Division of Endocrinology, Department of Pediatrics, University of Colorado Denver Anschutz Medical Campus, Aurora, CO, 80045, USA
| | - Laura Pyle
- Department of Pediatrics, University of Colorado Denver Anschutz Medical Campus, Aurora, CO, 80045, USA.,Department of Biostatics and Informatics, Colorado School of Public Health, Aurora, CO, 80045, USA
| | - Kristen J Nadeau
- Division of Endocrinology, Department of Pediatrics, University of Colorado Denver Anschutz Medical Campus, Aurora, CO, 80045, USA.,Center for Women's Health Research, Aurora, CO, USA
| | - Melanie Cree-Green
- Division of Endocrinology, Department of Pediatrics, University of Colorado Denver Anschutz Medical Campus, Aurora, CO, 80045, USA.,Department of Biostatics and Informatics, Colorado School of Public Health, Aurora, CO, 80045, USA
| | - Cecilia Diniz Behn
- Department of Applied Mathematics and Statistics, Colorado School of Mines, Golden, CO, 80401, USA.,Division of Endocrinology, Department of Pediatrics, University of Colorado Denver Anschutz Medical Campus, Aurora, CO, 80045, USA
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Yang G, Li C, Gong Y, Fang F, Tian H, Li J, Cheng X. Assessment of Insulin Resistance in Subjects with Normal Glucose Tolerance, Hyperinsulinemia with Normal Blood Glucose Tolerance, Impaired Glucose Tolerance, and Newly Diagnosed Type 2 Diabetes (Prediabetes Insulin Resistance Research). J Diabetes Res 2016; 2016:9270768. [PMID: 26770991 PMCID: PMC4685128 DOI: 10.1155/2016/9270768] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/16/2015] [Revised: 07/29/2015] [Accepted: 07/29/2015] [Indexed: 11/23/2022] Open
Abstract
AIM To evaluate the differences in insulin resistance (IR) among subjects with normal glucose tolerance (NGT), hyperinsulinemia with NGT (HINS), impaired glucose tolerance (IGT), and newly diagnosed type 2 diabetes mellitus (T2DM). METHODS 5 NGT, 25 HINS, 25 IGT, and 25 T2DM subjects participated in this research. The hyperinsulinemic-euglycemic clamp technique (HECT) was performed in all of them to evaluate IR levels. The relative factors influencing IR were evaluated. The simple insulin sensitivity indices were calculated, and the correlation between each index and the M value was analyzed. RESULTS The M values of NGT, HINS, IGT, and T2DM groups were 11.88 ± 2.93 mg · kg(-1) · min(-1), 6.23 ± 1.73 mg · kg(-1) · min(-1), 6.37 ± 2.12 mg · kg(-1) · min(-1), and 6.19 ± 1.89 mg · kg(-1) · min(-1), respectively. M values in HINS, IGT, and T2DM groups were lower than those in the NGT group (P = 0.005); however, the differences among the HINS, IGT, and T2DM groups were not statistically significant (P = 0.835). The independent factors influencing the M value were waistline and fasting insulin level (FINS). The simple insulin sensitivity indices, especially Matsuda and Gutt index, were significantly associated with the M value (P < 0.01). CONCLUSION IR existed in the HINS, IGT, and T2DM groups, and IR levels were consistent in the three groups. The independent factors influencing IR were waistline and FINS.
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Affiliation(s)
- Guang Yang
- Department of Geriatric Endocrinology, Chinese PLA General Hospital, No. 28 Fuxing Road, Beijing 100853, China
| | - Chunlin Li
- Department of Geriatric Endocrinology, Chinese PLA General Hospital, No. 28 Fuxing Road, Beijing 100853, China
- *Chunlin Li:
| | - Yanping Gong
- Department of Geriatric Endocrinology, Chinese PLA General Hospital, No. 28 Fuxing Road, Beijing 100853, China
| | - Fusheng Fang
- Department of Geriatric Endocrinology, Chinese PLA General Hospital, No. 28 Fuxing Road, Beijing 100853, China
| | - Hui Tian
- Department of Geriatric Endocrinology, Chinese PLA General Hospital, No. 28 Fuxing Road, Beijing 100853, China
| | - Jian Li
- Department of Geriatric Endocrinology, Chinese PLA General Hospital, No. 28 Fuxing Road, Beijing 100853, China
| | - Xiaoling Cheng
- Department of Geriatric Endocrinology, Chinese PLA General Hospital, No. 28 Fuxing Road, Beijing 100853, China
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Abstract
There is a general perception that increased physical activity will improve glucose homeostasis in all individuals. While this is an attractive concept, this conclusion may be overly simplistic and even misleading. The topic was reviewed extensively over 30 years ago and it was concluded that acute exercise enhances glucose uptake. However, in some cases the chronic influence of interventions utilizing exercise may have little effect on glucose metabolism. Moreover, insulin resistance often returns to near baseline levels within a couple of days following cessation of the exercise bout; leaving the overall effectiveness of the intervention in question. Since improving glucose homeostasis should be the focal endpoint of any intervention designed to mitigate the overwhelming degree of insulin resistance in individuals at risk for metabolic disease, it is essential to evaluate the key components of a successful approach.
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Affiliation(s)
- Tyler E Keshel
- Institute of Arctic Biology, University of Alaska-Fairbanks, Fairbanks, AK, USA
| | - Robert H Coker
- Institute of Arctic Biology, University of Alaska-Fairbanks, Fairbanks, AK, USA ; Center for Translational Research in Aging and Longevity, Department of Geriatrics, University of Arkansas for Medical Sciences, Little Rock, AR, USA
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Kim IY, Williams RH, Schutzler SE, Lasley CJ, Bodenner DL, Wolfe RR, Coker RH. Acute lysine supplementation does not improve hepatic or peripheral insulin sensitivity in older, overweight individuals. Nutr Metab (Lond) 2014; 11:49. [PMID: 25324894 PMCID: PMC4198625 DOI: 10.1186/1743-7075-11-49] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/16/2014] [Accepted: 08/28/2014] [Indexed: 01/09/2023] Open
Abstract
Context Lysine supplementation may have a positive influence on the regulation of glucose metabolism but it has not been tested in the geriatric population. Objective: We evaluated the impact of acute lysine supplementation using three randomized experimental scenarios: 1) oral glucose alone (control), 2) oral glucose and low-dose lysine (2 grams), and oral glucose and high dose lysine (5 grams) lysine in 7 older (66 ± 1 years/age), overweight/obese (BMI = 28 ± 2 kg/m2) individuals. Methods We utilized a dual tracer technique (i.e., [6,6-2H2] glucose primed constant infusion and 1-[13C] glucose oral ingestion) during an oral glucose tolerance test (OGTT) to examine differences in hepatic and peripheral insulin sensitivity under all three scenarios. Results Post-absorptive plasma glucose and insulin concentrations were not different between the three trials. Similarly, the response of glucose and insulin concentrations during the oral glucose tolerance tests (OGTT) was similar in the three trials. The results of the Matsuda index (ISI/M) were also not different between the three trials. As an index of hepatic insulin sensitivity, there were no significant differences in the endogenous glucose rate of appearance (glucose Ra) for control, 2 g lysine and 5 g lysine (1.2 ± 0.1, 1.1 ± 0.1, 1.3 ± 0.1 mg•kg-1•min-1), respectively. With respect to peripheral insulin sensitivity, there were no significant differences in the glucose rate of disappearance (glucose Rd) for control, 2 g lysine and 5 g lysine (4.2 ± 0.1, 4.3 ± 0.2, and 4.5 ± 0.4 mg•kg-1•min-1), respectively. Conclusions Previous studies in younger participants have suggested that lysine may have a beneficial effect on glucose metabolism. However, acute lysine supplementation in the older population does not facilitate beneficial changes in glucose Ra or glucose Rd. Electronic supplementary material The online version of this article (doi:10.1186/1743-7075-11-49) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- Il-Young Kim
- Center for Translational Research in Aging and Longevity, Reynolds Institute on Aging, University of Arkansas for Medical Sciences, Little Rock, AR USA
| | - Rick H Williams
- Center for Translational Research in Aging and Longevity, Reynolds Institute on Aging, University of Arkansas for Medical Sciences, Little Rock, AR USA
| | - Scott E Schutzler
- Center for Translational Research in Aging and Longevity, Reynolds Institute on Aging, University of Arkansas for Medical Sciences, Little Rock, AR USA
| | - Cosby J Lasley
- Center for Translational Research in Aging and Longevity, Reynolds Institute on Aging, University of Arkansas for Medical Sciences, Little Rock, AR USA
| | - Donald L Bodenner
- Center for Translational Research in Aging and Longevity, Reynolds Institute on Aging, University of Arkansas for Medical Sciences, Little Rock, AR USA
| | - Robert R Wolfe
- Center for Translational Research in Aging and Longevity, Reynolds Institute on Aging, University of Arkansas for Medical Sciences, Little Rock, AR USA
| | - Robert H Coker
- Center for Alaska Native Health Research, Institute of Arctic Biology, University of Alaska-Fairbanks, 902 North Koyukuk Drive, Fairbanks, AK 99775-7000 USA
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Coker RH, Hays NP, Williams RH, Xu L, Wolfe RR, Evans WJ. Bed rest worsens impairments in fat and glucose metabolism in older, overweight adults. J Gerontol A Biol Sci Med Sci 2013; 69:363-70. [PMID: 23902932 DOI: 10.1093/gerona/glt100] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022] Open
Abstract
BACKGROUND The effects of bed rest on the dysregulation of fatty acid and glucose metabolism have not been addressed in the older population. OBJECTIVE We examined the effect of 10 days of bed rest on fatty acid kinetics and hepatic and peripheral insulin resistance in aging. METHODS We utilized an octreotide, basal glucagon replacement, multistage insulin infusion, and the concomitant infusion of [6,6 (2)H₂]glucose to derive insulin-mediated suppression of glucose production and insulin-stimulated glucose disposal in nine older, overweight individuals (body mass index 28.1 ± 1.7 kg m(-2); 39.9% ± 1.9% fat). During the multistage insulin infusion, we also infused [1-(13)C]palmitate to examine free fatty acid rate of appearance (R(a)). RESULTS Body weight, % body fat, and energy metabolism did not change with bed rest. There was a significant decrease (-2291 ± 316 cm(3)) in visceral fat, and no change in abdominal subcutaneous fat with bed rest. Insulin-mediated suppression of glucose production was modest prior to bed rest and was further reduced (>15% ± 2%) by bed rest. There was also a minor decrease in the insulin-mediated suppression of free fatty acid R(a) after bed rest and, as a consequence, a small variation in plasma free fatty acid from pre- to post-bed rest in the first stage of the multistage insulin infusion. There was also a significant bed rest-induced decline (>2.0 ± 0.6 mg kg FFM(-1) min(-1)) in insulin-stimulated glucose disposal. CONCLUSIONS Preexisting impairments in insulin sensitivity are worsened by bed rest and seem linked to alterations in the regulation of free fatty acid in older, overweight individuals.
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Affiliation(s)
- Robert H Coker
- Center for Alaska Native Health Research, Institute of Arctic Biology, 311 Irving I, Box 757000, University of Alaska Fairbanks, Fairbanks, AK 99775-7000.
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Bendsen NT, Haugaard SB, Larsen TM, Chabanova E, Stender S, Astrup A. Effect of trans-fatty acid intake on insulin sensitivity and intramuscular lipids--a randomized trial in overweight postmenopausal women. Metabolism 2011; 60:906-13. [PMID: 21397284 DOI: 10.1016/j.metabol.2011.01.009] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/07/2010] [Revised: 12/06/2010] [Accepted: 01/20/2011] [Indexed: 11/18/2022]
Abstract
Intake of industrially produced trans-fatty acids (TFA) has been linked to increased risk of type 2 diabetes mellitus in observational studies. We investigated the causality of this association by examining if a high intake of TFA impairs measures of glucose homeostasis and induces intramuscular lipid deposition in abdominally obese women. In a double-blind, parallel dietary intervention study, 52 healthy but overweight postmenopausal women were randomized to receive either partially hydrogenated soybean oil (15 g/d TFA) or a control oil (mainly oleic and palmitic acid) for 16 weeks. Three markers of glucose homeostasis and 4 markers of lipolysis were derived from glucose, insulin, C-peptide, nonesterified fatty acid, and glycerol concentrations during a 3-hour frequent sampling oral glucose tolerance test. Intramuscular lipids were assessed by magnetic resonance spectroscopy. Forty-nine women completed the study. Insulin sensitivity (assessed by ISI(composite)), β-cell function (the disposition index), and the metabolic clearance rate of insulin were not significantly affected by the dietary intervention. Neither was the ability of insulin to suppress plasma nonesterified fatty acid and glycerol during oral glucose ingestion nor the intramuscular lipid deposition. In conclusion, high TFA intake did not affect glucose metabolism over 16 weeks in postmenopausal overweight women. A study population with a stronger predisposition to insulin resistance and/or a longer duration of exposure may be required for insulin sensitivity to be affected by intake of industrial TFA.
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Affiliation(s)
- Nathalie T Bendsen
- Department of Human Nutrition, Faculty of Life Sciences, University of Copenhagen, DK-1958 Frederiksberg, Denmark
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Mooren FC, Krüger K, Völker K, Golf SW, Wadepuhl M, Kraus A. Oral magnesium supplementation reduces insulin resistance in non-diabetic subjects - a double-blind, placebo-controlled, randomized trial. Diabetes Obes Metab 2011; 13:281-4. [PMID: 21205110 DOI: 10.1111/j.1463-1326.2010.01332.x] [Citation(s) in RCA: 109] [Impact Index Per Article: 8.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
The incidence of insulin resistance and metabolic syndrome correlates with the availability of magnesium (Mg). We studied the effect of oral Mg supplementation on insulin sensitivity and other characteristics of the metabolic syndrome in normomagnesemic, overweight, insulin resistant, non-diabetic subjects. Subjects were tested for eligibility using oral glucose tolerance test (OGTT) and subsequently randomized to receive either Mg-aspartate-hydrochloride (n = 27) or placebo (n = 25) for 6 months. As trial endpoints, several indices of insulin sensitivity, plasma glucose, serum insulin, blood pressure and lipid profile were determined. Mg supplementation resulted in a significant improvement of fasting plasma glucose and some insulin sensitivity indices (ISIs) compared to placebo. Blood pressure and lipid profile did not show significant changes. The results provide significant evidence that oral Mg supplementation improves insulin sensitivity even in normomagnesemic, overweight, non-diabetic subjects emphasizing the need for an early optimization of Mg status to prevent insulin resistance and subsequently type 2 diabetes.
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Coker RH, Williams RH, Yeo SE, Kortebein PM, Bodenner DL, Kern PA, Evans WJ. The impact of exercise training compared to caloric restriction on hepatic and peripheral insulin resistance in obesity. J Clin Endocrinol Metab 2009; 94:4258-66. [PMID: 19808853 PMCID: PMC2775654 DOI: 10.1210/jc.2008-2033] [Citation(s) in RCA: 68] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/21/2023]
Abstract
CONTEXT It has been difficult to distinguish the independent effects of caloric restriction versus exercise training on insulin resistance. OBJECTIVE Utilizing metabolic feeding and supervised exercise training, we examined the influence of caloric restriction vs. exercise training with and without weight loss on hepatic and peripheral insulin resistance. DESIGN, PARTICIPANTS, AND INTERVENTION Thirty-four obese, older subjects were randomized to: caloric restriction with weight loss (CR), exercise training with weight loss (EWL), exercise training without weight loss (EX), or controls. Based on an equivalent caloric deficit in EWL and CR, we induced matched weight loss. Subjects in the EX group received caloric compensation. Combined with [6,6(2)H(2)]glucose, an octreotide, glucagon, multistage insulin infusion was performed to determine suppression of glucose production (SGP) and insulin-stimulated glucose disposal (ISGD). Computed tomography scans were performed to assess changes in fat distribution. RESULTS Body weight decreased similarly in EWL and CR, and did not change in EX and controls. The reduction in visceral fat was significantly greater in EWL (-71 +/- 15 cm(2)) compared to CR and EX. The increase in SGP was also almost 3-fold greater (27 +/- 2%) in EWL. EWL and CR promoted similar improvements in ISGD [+2.5 +/- 0.4 and 2.4 +/- 0.9 mg x kg fat-free mass (FFM)(-1) x min(-1)], respectively. CONCLUSIONS EWL promoted the most significant reduction in visceral fat and the greatest improvement in SGP. Equivalent increases in ISGD were noted in EWL and CR, whereas EX provided a modest improvement. Based on our results, EWL promoted the optimal intervention-based changes in body fat distribution and systemic insulin resistance.
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Affiliation(s)
- Robert H Coker
- Central Arkansas Veterans Healthcare System, University of Arkansas for Medical Sciences, Little Rock, Arkansas 72205, USA.
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Wang H, Hays NP, Das SK, Craig RL, Chu WS, Sharma N, Elbein SC. Phenotypic and molecular evaluation of a chromosome 1q region with linkage and association to type 2 diabetes in humans. J Clin Endocrinol Metab 2009; 94:1401-8. [PMID: 19141583 PMCID: PMC2682467 DOI: 10.1210/jc.2008-2132] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/30/2008] [Accepted: 01/07/2009] [Indexed: 11/19/2022]
Abstract
OBJECTIVE Linkage to type 2 diabetes (T2D) is well replicated on chromosome 1q21-q23. Within this region, T2D was associated with common single nucleotide polymorphisms that marked an extended linkage disequilibrium block, including the liver pyruvate kinase gene (PKLR), in several European-derived populations. In this study we sought to determine the molecular basis for the association and the phenotypic consequences of the risk haplotype. RESEARCH DESIGN AND METHODS Genes surrounding PKLR were resequenced in European-American and African-American cases and controls, and association with T2D was tested. Copy number variants (CNVs) were tested for four regions with real-time PCR. Expression of genes in the region was tested in adipose and muscle from nondiabetic subjects with each genotype. Insulin secretion, insulin sensitivity, and hepatic glucose production were tested in nondiabetic individuals with each haplotype combination. RESULTS No coding variant in the region was associated with T2D. CNVs were rare and not associated with T2D. PKLR was not expressed in available tissues, but expression of genes HCN3, CLK2, SCAMP3, and FDPS was not associated with haplotype combinations in adipose or muscle. Haplotype combinations were not associated with insulin secretion or peripheral insulin sensitivity, but homozygous carriers of the risk haplotype had increased hepatic glucose production during hyperinsulinemia. CONCLUSIONS Noncoding variants in the PKLR region likely alter gene expression of one or more genes. Our extensive physiological and molecular studies suggest increased hepatic glucose production and reduced hepatic insulin sensitivity, thus pointing to PKLR itself as the most likely candidate gene in this population.
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Affiliation(s)
- Hua Wang
- Department of Internal Medicine, Division of Endocrinology, University of Arkansas for Medical Sciences, Little Rock, Arkansas 72205, USA
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Alvarez JA, Bush NC, Hunter GR, Brock DW, Gower BA. Ethnicity and weight status affect the accuracy of proxy indices of insulin sensitivity. Obesity (Silver Spring) 2008; 16:2739-44. [PMID: 18927554 PMCID: PMC2779542 DOI: 10.1038/oby.2008.437] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/28/2023]
Abstract
This study tested the hypotheses that correlations between direct measures of insulin sensitivity and proxy indices of insulin sensitivity derived from fasting values, (i) would not be affected by ethnicity, and (ii) would be stronger in overweight vs. weight-reduced states. We further hypothesized that associations between proxy indices and fat distribution would be similar to those between directly measured insulin sensitivity and fat distribution. Testing was performed in weight-stable conditions in 59 African-American (AA) and 62 white-American (WA) overweight, premenopausal women before and after a weight loss intervention. Subjects were retested 1 year following weight loss. Proxy indices were correlated against the insulin sensitivity index S(I) determined via minimal modeling. Fat distribution was assessed using computed tomography. Correlations between Si and proxy indices were consistently stronger among overweight women (r = 0.44-0.52) vs. weight-reduced women (r = 0.18-0.32), and among AA (r = 0.49-0.56, baseline; 0.24-0.36, weight-reduced) vs. WA (r = 0.38-0.46, baseline; 0.19-0.31, weight-reduced). Among subjects who regained >3 kg after 1 year, correlations between S(I) and proxy indices were similar to those observed at baseline, whereas correlations were weak among women who maintained their reduced body weight. S(I) and all proxy indices were similarly correlated with intra-abdominal adipose tissue (IAAT) at baseline, but not after weight loss. In conclusion, correlations between S(I) and proxy indices were affected by both ethnicity and weight status. If proxy indices are used in multiethnic populations, or in populations including both lean and overweight/obese subjects, data should be interpreted with caution.
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Affiliation(s)
- Jessica A Alvarez
- Department of Nutrition Sciences, University of Alabama at Birmingham, Birmingham, Alabama, USA.
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Bloem CJ, Chang AM. Short-term exercise improves beta-cell function and insulin resistance in older people with impaired glucose tolerance. J Clin Endocrinol Metab 2008; 93:387-92. [PMID: 18000089 PMCID: PMC2243226 DOI: 10.1210/jc.2007-1734] [Citation(s) in RCA: 67] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
BACKGROUND There is a high prevalence of diabetes and impaired glucose tolerance (IGT) in the older population. Normal aging is associated with insulin resistance and impaired insulin secretion, with greater defects in people with IGT. Short-term exercise has been found to increase insulin sensitivity, but little is known about acute exercise effects on beta-cell function in older people with IGT. METHODS We assessed the effects of 7 consecutive days of supervised aerobic exercise (1 h/d at 60-70% heart rate reserve) in 12 sedentary older people with IGT. Screening included oral glucose tolerance test, stress/maximal O(2) uptake test, and dual-energy x-ray absorptiometry scan. Participants had a frequently sampled iv glucose tolerance test at baseline and 15-20 h after the seventh exercise session. Insulin sensitivity (S(I)), glucose disappearance constant (Kg, a measure of iv glucose tolerance), acute insulin response to glucose (AIRg), and disposition index (AIRg x S(I)), a measure of beta-cell function in relation to insulin resistance, were calculated. RESULTS Exercise was well tolerated. Body weight, fasting glucose, fasting insulin, and iv glucose tolerance were unchanged with exercise. S(I) increased by 59%, AIRg decreased by 12%, and disposition index increased by 31%. There was no significant change in fasting lipid, catecholamine, leptin, or adiponectin levels. CONCLUSIONS Short-term exercise not only improved insulin resistance but also significantly enhanced beta-cell function in older people with IGT. These effects of short-term exercise on beta-cell function cannot be explained by changes in body weight or circulating levels of lipids, leptin, adiponectin, or catecholamines.
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Affiliation(s)
- Cathie J Bloem
- Department of Internal Medicine, University of Michigan, Ann Arbor, Michigan 49109, USA
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Bibliography. Current world literature. Diabetes and the endocrine pancreas II. Curr Opin Endocrinol Diabetes Obes 2007; 14:329-57. [PMID: 17940461 DOI: 10.1097/med.0b013e3282c3a898] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
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