201
|
Petersen KF, Dufour S, Feng J, Befroy D, Dziura J, Man CD, Cobelli C, Shulman GI. Increased prevalence of insulin resistance and nonalcoholic fatty liver disease in Asian-Indian men. Proc Natl Acad Sci U S A 2006; 103:18273-7. [PMID: 17114290 PMCID: PMC1693873 DOI: 10.1073/pnas.0608537103] [Citation(s) in RCA: 283] [Impact Index Per Article: 15.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023] Open
Abstract
Type 2 diabetes mellitus (T2DM) is strongly associated with obesity in most, but not all, ethnic groups, suggesting important ethnic differences in disease susceptibility. Although it is clear that insulin resistance plays a major role in the pathogenesis of T2DM and that insulin resistance is strongly associated with increases in hepatic (HTG) and/or intramyocellular lipid content, little is known about the prevalence of insulin resistance and potential differences in intracellular lipid distribution among healthy, young, lean individuals of different ethnic groups. To examine this question, 482 young, lean, healthy, sedentary, nonsmoking Eastern Asians (n = 49), Asian-Indians (n = 59), Blacks (n = 48), Caucasians (n = 292), and Hispanics (n = 34) underwent an oral glucose tolerance test to assess whole-body insulin sensitivity by an insulin sensitivity index. In addition, intramyocellular lipid and HTG contents were measured by using proton magnetic resonance spectroscopy. The prevalence of insulin resistance, defined as the lower quartile of insulin sensitivity index, was approximately 2- to 3-fold higher in the Asian-Indians compared with all other ethnic groups, and this could entirely be attributed to a 3- to 4-fold increased prevalence of insulin resistance in Asian-Indian men. This increased prevalence of insulin resistance in the Asian-Indian men was associated with an approximately 2-fold increase in HTG content and plasma IL-6 concentrations compared with Caucasian men. These data demonstrate important ethnic and gender differences in the pathogenesis of insulin resistance in Asian-Indian men and have important therapeutic implications for treatment of T2DM and for the development of steatosis-related liver disease in this ethnic group.
Collapse
Affiliation(s)
| | - Sylvie Dufour
- Howard Hughes Medical Institute, Yale University School of Medicine, New Haven, CT 06536; and
| | - Jing Feng
- Departments of *Internal Medicine and
| | | | | | - Chiara Dalla Man
- Department of Information Engineering, University of Padua, 35122 Padua, Italy
| | - Claudio Cobelli
- Department of Information Engineering, University of Padua, 35122 Padua, Italy
| | - Gerald I. Shulman
- Departments of *Internal Medicine and
- Cellular and Molecular Physiology and
- Howard Hughes Medical Institute, Yale University School of Medicine, New Haven, CT 06536; and
- To whom correspondence should be addressed at:
Howard Hughes Medical Institute, Yale University School of Medicine, P.O. Box 9812, New Haven, CT 06520. E-mail:
| |
Collapse
|
202
|
Ukkola O. Operative risk factors in the metabolic syndrome: is it lipids and high blood pressure or are there direct vascular effects of insulin resistance and obesity? Curr Cardiol Rep 2006; 8:427-32. [PMID: 17059794 DOI: 10.1007/s11886-006-0100-4] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Abstract
The metabolic syndrome is associated with an increased risk for cardiovascular disease. Dyslipidemia, high blood pressure, and impaired glucose tolerance, components of the metabolic syndrome, are all clearly atherogenic. Insulin resistance is an important correlate of other risk factors. Excess abdominal fat, as often seen in overweight people and commonly observed in obese individuals, is the single most important central feature of the metabolic syndrome. In addition to insulin resistance, an excess amount of abdominal fat is associated with all the features of metabolic clustering. Adipocytes secrete several peptide hormones that have been related to the metabolic syndrome and related cardiovascular disease. The role of traditional versus novel adipose tissue-related risk factors in the background of atherosclerosis in the metabolic syndrome are discussed.
Collapse
Affiliation(s)
- Olavi Ukkola
- Department of Internal Medicine and Biocenter Oulu, University of Oulu, Kajaanintie 50/P.O. Box 5000, Oulu, FIN-90014, Finland.
| |
Collapse
|
203
|
Wang M, Fotsch C. Small-Molecule Compounds that Modulate Lipolysis in Adipose Tissue: Targeting Strategies and Molecular Classes. ACTA ACUST UNITED AC 2006; 13:1019-27. [DOI: 10.1016/j.chembiol.2006.09.010] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/22/2006] [Revised: 09/21/2006] [Accepted: 09/22/2006] [Indexed: 12/31/2022]
|
204
|
Huptas S, Geiss HC, Otto C, Parhofer KG. Effect of atorvastatin (10 mg/day) on glucose metabolism in patients with the metabolic syndrome. Am J Cardiol 2006; 98:66-9. [PMID: 16784923 DOI: 10.1016/j.amjcard.2006.01.055] [Citation(s) in RCA: 59] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/27/2005] [Revised: 01/17/2006] [Accepted: 01/17/2006] [Indexed: 10/24/2022]
Abstract
Large interventional studies have shown that statins may reduce the incidence of type 2 diabetes mellitus. However, it is uncertain whether short-term statin therapy can affect insulin sensitivity in patients with the metabolic syndrome. We evaluated the effect of atorvastatin (10 mg/day) in 10 insulin-resistant subjects (age 40 +/- 12 years, body mass index 33.6 +/- 5.2 kg/m(2), triglycerides 2.84 +/- 1.99 mmol/L [249 +/- 175 mg/dl], glucose 6.06 +/- 0.67 mmol/L [109 +/- 12 mg/dl)] using the homeostasis model assessment (HOMA) index (parameter of insulin resistance derived from fasting glucose and fasting insulin concentrations; 5.7 +/- 2.6) in a randomized placebo-controlled, double-blind, crossover study. Subjects were randomized to receive placebo or atorvastatin, each given for 6 weeks separated by a 6-week wash-out period. At the beginning and end of each treatment phase, the patients underwent an oral glucose tolerance test, a 72-hour continuous glucose measurement, and a detailed lipid determination, including a standardized fat tolerance test. Compared with placebo, atorvastatin resulted in a significant (p = 0.05) reduction in the HOMA index (-21%), fasting C-peptides (-18%), glucose (area under the curve during the oral glucose tolerance test, -7%), and a borderline (p = 0.08) reduction of insulin (-18%). The parameters derived from the continuous 72-hour glucose monitoring did not change. A significant reduction also occurred in the total and low-density lipoprotein cholesterol concentrations, although the fasting and postprandial triglyceride concentrations did not change significantly. However, we found a significant correlation between atorvastatin-induced changes in the HOMA and baseline HOMA and between the atorvastatin-induced changes in triglycerides and insulin concentrations. The free-fatty acid, interleukin-6, and high sensitivity C-reactive protein concentrations did not change. Our data indicated that in insulin-resistant, nondiabetic subjects, 6 weeks of atorvastatin (10 mg/day) resulted in significant improvement in insulin sensitivity.
Collapse
Affiliation(s)
- Sebastian Huptas
- Department of Internal Medicine II, Klinikum Grosshadern, Ludwig-Maximilians University, Munich, Germany
| | | | | | | |
Collapse
|
205
|
Yoshii H, Lam TKT, Gupta N, Goh T, Haber CA, Uchino H, Kim TTY, Chong VZ, Shah K, Fantus IG, Mari A, Kawamori R, Giacca A. Effects of portal free fatty acid elevation on insulin clearance and hepatic glucose flux. Am J Physiol Endocrinol Metab 2006; 290:E1089-97. [PMID: 16390863 DOI: 10.1152/ajpendo.00306.2005] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
We tested the hypothesis that, due to greater hepatic free fatty acid (FFA) load, portal delivery of FFAs, as in visceral obesity, induces hyperinsulinemia and increases endogenous glucose production to a greater extent than peripheral FFA delivery. For 5 h, 10 microeq.kg(-1).min(-1) portal oleate (n = 6), equidose peripheral oleate (n = 5), or saline (n = 6) were given intravenously to conscious dogs infused with a combination of portal and peripheral insulin to enable calculation of hepatic insulin clearance during a pancreatic euglycemic clamp. Peripheral FFAs were similar with both oleate treatments and were threefold greater than in controls. Portal FFAs were 1.5- to 2-fold greater with portal than with peripheral oleate. Peripheral insulin concentrations were greatest with portal oleate, intermediate with peripheral oleate (P < 0.001 vs. portal oleate or controls), and lowest in controls, consistent with corresponding reductions in plasma insulin clearance and hepatic insulin clearance. Although endogenous glucose production did not differ between the two routes of oleate delivery, total glucose output (endogenous glucose production plus glucose cycling) was greater with portal than with peripheral oleate (P < 0.001) despite the higher insulin levels. In conclusion, during euglycemic clamps in dogs, the main effect of short-term elevation in portal FFA is to generate peripheral hyperinsulinemia. This may, in the long term, contribute to the metabolic and cardiovascular risk of visceral obesity.
Collapse
Affiliation(s)
- Hidenori Yoshii
- Dept. of Physiology, Univ. of Toronto, Medical Sciences Bldg., Rm. 3336, Toronto, ON M5S1A8 Canada
| | | | | | | | | | | | | | | | | | | | | | | | | |
Collapse
|
206
|
Parhofer KG, Barrett PHR. Thematic review series: patient-oriented research. What we have learned about VLDL and LDL metabolism from human kinetics studies. J Lipid Res 2006; 47:1620-30. [PMID: 16720894 DOI: 10.1194/jlr.r600013-jlr200] [Citation(s) in RCA: 43] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Lipoprotein metabolism is the result of a complex network of many individual components. Abnormal lipoprotein concentrations can result from changes in the production, conversion, or catabolism of lipoprotein particles. Studies in hypolipoproteinemia and hyperlipoproteinemia have elucidated the processes that control VLDL secretion as well as VLDL and LDL catabolism. Here, we review the current knowledge regarding apolipoprotein B (apoB) metabolism, focusing on selected clinically relevant conditions. In hypobetalipoproteinemia attributable to truncations in apoB, the rate of secretion is closely linked to the length of apoB. On the other hand, in patients with the metabolic syndrome, it appears that substrate, in the form of free fatty acids, coupled to the state of insulin resistance can induce hypersecretion of VLDL-apoB. Studies in patients with familial hypercholesterolemia, familial defective apoB, and mutant forms of proprotein convertase subtilisin/kexin type 9 show that mutations in the LDL receptor, the ligand for the receptor, or an intracellular chaperone for the receptor are the most important determinants in regulating LDL catabolism. This review also demonstrates the variance of results within similar, or even the same, phenotypic conditions. This underscores the sensitivity of metabolic studies to methodological aspects and thus the importance of the inclusion of adequate controls in studies.
Collapse
|
207
|
Ribeiro Filho FF, Mariosa LS, Ferreira SRG, Zanella MT. [Visceral fat and metabolic syndrome: more than a simple association]. ACTA ACUST UNITED AC 2006; 50:230-8. [PMID: 16767289 DOI: 10.1590/s0004-27302006000200009] [Citation(s) in RCA: 52] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/21/2023]
Abstract
Metabolic syndrome (MS) is seen nowadays as a worldwide epidemic event associated with high cardiovascular morbi-mortality and high socioeconomic cost. The ponderal gain is an independent predictor for the development of MS, although not all obese individuals present it. On the other hand, some populations with low obesity prevalence present high prevalence of MS and cardiovascular mortality. The distribution of corporal fat is relevant and visceral fat (VF), specifically, seems to be the link between adipose tissue and insulin resistance (IR), a mean feature of MS. Adipose tissue is now considered a complex organ with multiple functions. VF presents metabolic properties, which are different from the gluteo-femoral subcutaneous fat and related to IR. Several studies show the narrow relationship of abdominal adiposity with the glucose tolerance, hyperinsulinemia, hypertriglyceridemia and arterial hypertension. More than a simple association, recently it is thought that the VF plays a central part in the physiopathology of MS. Consequently, the quantification of VF plays an important role to identify individuals with larger risk for development of MS, who should be chosen for early interventions in the attempt of reducing the impact of metabolic abnormalities on cardiovascular mortality. This article discusses particularities of the central distribution of fat in MS context, possible physiopathogenic mechanisms related to the VF and available methods for the evaluation of abdominal adiposity.
Collapse
|
208
|
Kreier F, Kap YS, Mettenleiter TC, van Heijningen C, van der Vliet J, Kalsbeek A, Sauerwein HP, Fliers E, Romijn JA, Buijs RM. Tracing from fat tissue, liver, and pancreas: a neuroanatomical framework for the role of the brain in type 2 diabetes. Endocrinology 2006; 147:1140-7. [PMID: 16339209 DOI: 10.1210/en.2005-0667] [Citation(s) in RCA: 135] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
The hypothalamus uses hormones and the autonomic nervous system to balance energy fluxes in the body. Here we show that the autonomic nervous system has a distinct organization in different body compartments. The same neurons control intraabdominal organs (intraabdominal fat, liver, and pancreas), whereas sc adipose tissue located outside the abdominal compartment receives input from another set of autonomic neurons. This differentiation persists up to preautonomic neurons in the hypothalamus, including the biological clock, that have a distinct organization depending on the body compartment they command. Moreover, we demonstrate a neuronal feedback from adipose tissue that reaches the brainstem. We propose that this compartment-specific organization offers a neuroanatomical perspective for the regional malfunction of organs in type 2 diabetes, where increased insulin secretion by the pancreas and disturbed glucose metabolism in the liver coincide with an augmented metabolic activity of visceral compared with sc adipose tissue.
Collapse
Affiliation(s)
- Felix Kreier
- Netherlands Institute for Brain Research, Meibergdreef 33, 1105 AZ Amsterdam, The Netherlands.
| | | | | | | | | | | | | | | | | | | |
Collapse
|
209
|
Bergman RN, Kim SP, Catalano KJ, Hsu IR, Chiu JD, Kabir M, Hucking K, Ader M. Why visceral fat is bad: mechanisms of the metabolic syndrome. Obesity (Silver Spring) 2006; 14 Suppl 1:16S-19S. [PMID: 16642958 DOI: 10.1038/oby.2006.277] [Citation(s) in RCA: 259] [Impact Index Per Article: 14.4] [Reference Citation Analysis] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Affiliation(s)
- Richard N Bergman
- Department of Physiology and Biophysics, Keck School of Medicine, University of Southern California, Los Angeles, CA, USA.
| | | | | | | | | | | | | | | |
Collapse
|
210
|
Affiliation(s)
- Claire Z Larter
- The Storr Liver Unit, Westmead's Millennium Institute, University of Sydney at Westmead Hospital, Westmead, NSW 2145, Australia
| | | |
Collapse
|
211
|
O'Leary VB, Marchetti CM, Krishnan RK, Stetzer BP, Gonzalez F, Kirwan JP. Exercise-induced reversal of insulin resistance in obese elderly is associated with reduced visceral fat. J Appl Physiol (1985) 2005; 100:1584-9. [PMID: 16373444 PMCID: PMC7037693 DOI: 10.1152/japplphysiol.01336.2005] [Citation(s) in RCA: 171] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Exercise improves glucose metabolism and delays the onset and/or reverses insulin resistance in the elderly by an unknown mechanism. In the present study, we examined the effects of exercise training on glucose metabolism, abdominal adiposity, and adipocytokines in obese elderly. Sixteen obese men and women (age = 63 +/- 1 yr, body mass index = 33.2 +/- 1.4 kg/m2) participated in a 12-wk supervised exercise program (5 days/wk, 60 min/day, treadmill/cycle ergometry at 85% of heart rate maximum). Visceral fat (VF), subcutaneous fat, and total abdominal fat were measured by computed tomography. Fat mass and fat-free mass were assessed by hydrostatic weighing. An oral glucose tolerance test was used to determine changes in insulin resistance. Exercise training increased maximal oxygen consumption (21.3 +/- 0.8 vs. 24.3 +/- 1.0 ml.kg(-1).min(-1), P < 0.0001), decreased body weight (P < 0.0001) and fat mass (P < 0.001), while fat-free mass was not altered (P > 0.05). VF (176 +/- 20 vs. 136 +/- 17 cm2, P < 0.0001), subcutaneous fat (351 +/- 34 vs. 305 +/- 28 cm2, P < 0.03), and total abdominal fat (525 +/- 40 vs. 443 +/- 34 cm2, P < 0.003) were reduced through training. Circulating leptin was lower (P < 0.003) after training, but total adiponectin and tumor necrosis factor-alpha remained unchanged. Insulin resistance was reversed by exercise (40.1 +/- 7.7 vs. 27.6 +/- 5.6 units, P < 0.01) and correlated with changes in VF (r = 0.66, P < 0.01) and maximal oxygen consumption (r = -0.48, P < 0.05) but not adipocytokines. VF loss after aerobic exercise training improves glucose metabolism and is associated with the reversal of insulin resistance in older obese men and women.
Collapse
Affiliation(s)
- Valerie B O'Leary
- Schwartz Center for Metabolism and Nutrition, Case Western Reserve University School of Medicine, Cleveland, OH 44109-1998, USA
| | | | | | | | | | | |
Collapse
|
212
|
Gastaldelli A, Sironi AM, Ciociaro D, Positano V, Buzzigoli E, Giannessi D, Lombardi M, Mari A, Ferrannini E. Visceral fat and beta cell function in non-diabetic humans. Diabetologia 2005; 48:2090-6. [PMID: 16086140 DOI: 10.1007/s00125-005-1891-3] [Citation(s) in RCA: 31] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/19/2005] [Accepted: 05/01/2005] [Indexed: 10/25/2022]
Abstract
AIMS/HYPOTHESIS Preferential visceral adipose tissue (VAT) accumulation has been clearly associated with insulin resistance. In contrast, the impact of visceral obesity on beta cell function is controversial. METHODS In 62 non-diabetic women and men (age 24-69 years, BMI 21-39 kg/m2), we measured VAT and subcutaneous adipose tissue (SAT) fat mass by magnetic resonance imaging. We also measured insulin secretion and beta cell function by C-peptide deconvolution and physiological modelling of data from a frequently sampled, 75-g, 3-h OGTT, respectively. RESULTS VAT (range 0.1-3.1 kg) was strongly related to sex, age and BMI; SAT was related to sex and BMI. Controlling for sex, age, BMI and SAT by multivariate analysis, excess VAT was associated with a clinical phenotype comprising higher plasma glucose levels, BP, heart rate and serum transaminases. The corresponding metabolic phenotype consisted of insulin resistance (partial r=-0.38) and hyperinsulinaemia (partial r=0.29). The latter, however, was appropriate for the degree of insulin resistance regardless of obesity and abdominal fat distribution. Moreover, none of the model-derived parameters describing beta cell function (glucose sensitivity, rate sensitivity and potentiation) was independently associated with excess VAT. CONCLUSIONS/INTERPRETATION In non-diabetic Caucasian adults of either sex, preferential visceral fat deposition in itself is part of an insulin-resistant phenotype. The insulin secretory response to a physiological challenge is increased to fully compensate for the insulin resistance, but the dynamics of beta cell function (glucose sensitivity, rate sensitivity and potentiation) are largely preserved.
Collapse
Affiliation(s)
- A Gastaldelli
- CNR Institute of Clinical Physiology, University of Pisa School of Medicine, Pisa, Italy.
| | | | | | | | | | | | | | | | | |
Collapse
|