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Query: UMLS:C0011860 (type 2 diabetes)
 57,723 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

During the past decade, the potential implications of insulin resistance were recognised by clinicians ranging from endocrinologists to cardiologists. Central to this expanding interest is Reaven's hypothesis that tissue resistance to the effects of insulin is a factor linking various metabolic disorders and coronary heart disease. This review critically describes the different approaches for the evaluation of insulin sensitivity in vivo. Qualities and limitations of several investigative techniques are discussed, such as anthropometric indexes, basal biological indexes, insulin suppression tests and insulin tolerance tests. The two most widely used methods for quantifying insulin sensitivity are the euglycaemic hyperinsulinaemic clamp and the intravenous glucose tolerance test with minimal model analysis. Insulin resistance occurs in many aetiologically diverse human disorders. Genetic syndromes with extreme insulin resistance are very uncommon. Insulin resistance is frequently associated with obesity, type 2 diabetes and essential hypertension. The insulin resistance syndrome called syndrome X includes impaired insulin-mediated glucose uptake, impaired glucose tolerance, hyperinsulinaemia, hypertension, dyslipidaemia and haemostatic disorders. Finally, the clinical significance of high values of insulin sensitivity is discussed.
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PMID:[In vivo evaluation of insulin sensitivity and clinical applications]. 975 76

Several recent studies indicate that type 2 diabetes, arterial hypertension, lipid disorders as well as visceral obesity are coronary risk factors which might belong to a syndrome which is caused by decreased insulin sensitivity with compensatory hyperinsulinaemia. More than 50% of patients with essential hypertension have some degree of insulin resistance, but in contrast to dyslipoproteinaemia and glucose intolerance the causal relation between insulin resistance and elevated arterial blood pressure appears not to be as evident. One explanation is that the link between blood pressure and insulin sensitivity might be mainly related to concomitant obesity. Accordingly, obesity can be associated with an increased activity of the sympathetic nervous system, elevated plasma levels of the vasoconstrictor endothelin-1, and decreased insulin-induced endothelium-dependent vasodilation. Furthermore, adipocytes can secrete vasogenic peptides, such as angiotensinogen. Since insulin resistance is a polygenic disorder, the two basic genetic approaches we follow is to identify genetic defects of insulin action in cells of patients with inherited syndromes of insulin resistance and to characterize molecular mechanisms of insulin regulated gene expression. The results show that insulin can affect the expression rate of various genes, e.g. involved in cholesterol and fatty acid metabolism, by modulating the activity of transcription factors coupled to the MAP kinase cascade and that a genetic postreceptor defect in these intracellular signaling pathways might have a pleiotropic effect on cell metabolism and clinical phenotype.
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PMID:Metabolic syndrome and hypertension: pathophysiology and molecular basis of insulin resistance. 983 75

Insulin action starts with binding to a membrane receptor (insulin receptor-tyrosine kinase) and with activating an insulin receptor substrate 1 (IRS-1) and substrate 2 (IRS-2). Insulin receptors interact at least with three cascade reactions, phosphorylating G proteins and IRS-1, that activate PLC "ras" and PI-3-K. NIDDM can be defined as a disease caused by defective transduction of insulin signals and IR as a complex phenotype manifesting itself, emphasized by individual and environmental factors, in the cellular systems of signal transduction. IRS is a syndrome characterized by NIDDM, hypertension, visceral obesity, CHD: the X syndrome. Up to day the described mutations of the insulin-receptor gene are rare (e.g. the leprechaunism): genetic IR. Obesity is the principal cause of IR by receptorial and post-receptorial defects: metabolic IR. The obese skeletal muscle shows a reduction of insulin receptor and IRS-1 phosphorylation and of PI-3-K activation; the scarce expression of these proteins would determine the muscular IR. IR is a pattern of essential hypertension. Hypertension, dyslipidemia and abnormality of glucose metabolism are linked by IR. The so called high erythrocyte Na(+)-Li+ counter-transport is a new biochemical marker for IR and hypertension. These drugs can reduce IR: metformin, sulphonilureas, fibrats, dexfenfluramine, troglitazone, doxazosin, ACE-inhibitors.
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PMID:[Insulin resistance. Receptor and post-receptor abnormalities]. 984 54

The human insulin-resistance syndromes, type 2 diabetes, obesity, combined hyperlipidaemia and essential hypertension, are complex disorders whose genetic basis is unknown. The spontaneously hypertensive rat (SHR) is insulin resistant and a model of these human syndromes. Quantitative trait loci (QTLs) for SHR defects in glucose and fatty acid metabolism, hypertriglyceridaemia and hypertension map to a single locus on rat chromosome 4. Here we combine use of cDNA microarrays, congenic mapping and radiation hybrid (RH) mapping to identify a defective SHR gene, Cd36 (also known as Fat, as it encodes fatty acid translocase), at the peak of linkage to these QTLs. SHR Cd36 cDNA contains multiple sequence variants, caused by unequal genomic recombination of a duplicated ancestral gene. The encoded protein product is undetectable in SHR adipocyte plasma membrane. Transgenic mice overexpressing Cd36 have reduced blood lipids. We conclude that Cd36 deficiency underlies insulin resistance, defective fatty acid metabolism and hypertriglyceridaemia in SHR and may be important in the pathogenesis of human insulin-resistance syndromes.
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PMID:Identification of Cd36 (Fat) as an insulin-resistance gene causing defective fatty acid and glucose metabolism in hypertensive rats. 991 87

As a major counterregulatory hormone of insulin, glucagon plays an important role in regulating glucose homeostasis through its binding to the glucagon receptor. Recently a missense mutation in the glucagon-receptor gene (Gly40Ser) was found to be associated with type 2 diabetes in France and Sardinia, with a frequency as high as 4.6% and 8.3%, respectively. This mutation was also found to be associated with essential hypertension in the white population with a frequency of 5.4%. To investigate the role of this mutation in the pathogenesis of type 2 diabetes and essential hypertension in Taiwanese population, we screened 121 normal controls, 213 unrelated subjects with type 2 diabetes, and 107 unrelated subjects with essential hypertension by use of polymerase chain reaction/restriction fragment length polymorphism (PCR-RFLP). None of the Taiwanese subjects recruited in the study had this receptor mutation. Our results demonstrate a strong genetic heterogeneity among the ethnic group and suggest that the Gly40Ser mutation of the glucagon receptor gene plays little role, if any, in the pathogenesis of type 2 diabetes and essential hypertension in the Taiwanese population.
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PMID:Screening for the Gly40Ser mutation in the glucagon receptor gene among patients with type 2 diabetes or essential hypertension in Taiwan. 1009 Apr 12

Insulin resistance is one of the cardinal pathophysiological components of the metabolic syndrome, type 2 diabetes, and frequently co-exists with essential hypertension. Although insulin resistance is defined as inadequate target organ (muscle, liver and fat) responsiveness and/or sensitivity to insulin, the primary defect may be located in the target organs themselves or at their remote controller--the central nervous system. One of the ways of resolving this dilemma is studying the mechanisms of action of drugs that have insulin-sensitizing properties. In this brief review we discuss how the known and potential insulin sensitizers: metformin, appetite suppressants, thiazolidinediones, and the new class of centrally acting antihypertensive drugs, I1-receptor agonists, may work.
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PMID:Insulin resistance: site of the primary defect or how the current and the emerging therapies work. 1021 39

The concomitant presence of diabetes mellitus and arterial hypertension significantly impairs myocardial function through a direct negative effect on cardiac myocytes, coronary microvessels and precipitation of atherosclerosis in major coronary arteries. The purpose of the present study was to establish to what extent non-insulin dependent diabetes mellitus (NIDDM) modified silent myocardial ischaemia (SMI) in patients with essential hypertension and without documented coronary artery disease (CAD). The study population consisted of 41 patients with essential arterial hypertension associated with NIDDM, treated with diet and oral hypoglycaemic agents (group I) and 40 patients with essential arterial hypertension without diabetes mellitus (group II). Both groups were comparable with respect to age, gender, duration, severity and complications of hypertension. A mean duration of diabetes mellitus in group I was 6.8 years. Conventional and automatic blood pressure and heart rate measurements, continuous ECG recordings, echocardiograms and laboratory tests were obtained in all patients. SMI was more frequent in group I than in group II (29.3% vs 12.5%, P < 0.05). In group I the total duration of SMI was longer (37.3 vs 2.8 min, P < 0.001) and the total number of silent episodes was larger (15.5 vs 2.6, P < 0.001). No inter-group differences were seen in conventional and automatic blood pressure and heart rate measurements. Both groups did not differ significantly in left ventricular mass index (LVMI) or the proportion of patients with left ventricular hypertrophy (LVH) (75.6% vs 60%). Lipid profile in both groups indicated an increased risk of CAD, but without significant differences. In conclusion, in patients with essential arterial hypertension and diabetes mellitus, the incidence and severity of SMI were clearly higher than in hypertensives with normal carbohydrate metabolism. Employment of modern diagnostic techniques in hypertensives permits identification of those at greater risk, which may have further clinical implications.
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PMID:Silent myocardial ischaemia in patients with essential arterial hypertension and non-insulin dependent diabetes mellitus. 1037 48

Familial clustering of altered albumin excretion and nephropathy risk has been described in both type 1 and type 2 diabetes; moreover, an association of micro-macroalbuminuria and diabetic retinopathy has been recently reported in a large number of white families with type 2 diabetes. Conflicting reports, mainly comparing affected with unaffected unrelated subjects, have suggested a possible role of some genotypes of the renin-angiotensin system in conferring nephropathy risk in type 2 diabetes. To examine the role of genetic factors in influencing albuminuria in families, we studied the relation of angiotensin-converting enzymes (ACE) and angiotensinogen (AGN) genotypes with albumin excretion rate in a population of affected siblings of type 2 diabetic probands. We determined ACE insertion/deletion polymorphism and two polymorphisms of the AGN gene (T174M and M235T) in 160 families with at least one affected member. Defining proband as the patient with the longest known duration of diabetes, we compared the allelic distribution in diabetic probands with and without altered albumin excretion and in their siblings. Allelic distribution of these polymorphisms was similar in the two groups of probands, as well as in their siblings. Identity-by-State (IBS) analysis showed a link between AGN locus and arterial hypertension in these siblings, which was independent from the degree of renal involvement. Thus, our findings suggest that in white families with type 2 diabetes, there is no linkage between the degree of albumin excretion and ACE and AGN polymorphisms, whereas the latter is related to arterial hypertension, as previously found in patients without diabetes but with essential hypertension.
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PMID:Polymorphisms of angiotensin-converting enzyme and angiotensinogen genes in type 2 diabetic sibships in relation to albumin excretion rate. 1058 8

A primary defect in the vascular action of insulin may be a key intermediate mechanism that links endothelial dysfunction with reduced insulin-mediated cellular glucose uptake in metabolic and cardiovascular disorders. The present study was designed to characterize more fully the relations between insulin action and endothelial function in male patients with essential hypertension (H, n=9) or type 2 diabetes (D, n=9) along with healthy control subjects (C) matched for age, body mass index, and lipid profile. They attended for measurement of whole-body insulin sensitivity (MCR) by the hyperinsulinemic clamp technique (day 1) and forearm vasoreactivity in response to intra-arterial infusions of insulin/glucose (day 2) and N(G)-monomethyl-L-arginine (L-NMMA) and norepinephrine (day 3) by bilateral venous-occlusion plethysmography. Results expressed as mean+/-SE MCR (mL/kg per minute) were 7.22+/-0. 99 (C), 6.32+/-0.78 (H), and 5.06+/-0.53 (D). Insulin/glucose-mediated vasodilation (IGMV) was 17.1+/-5.6% (C), 17. 2+/-5.5% (H), and 12.3+/-6.4% (D). L-NMMA vasoconstriction (LNV) was 37.9+/-5.1% (C), 37.5+/-2.3% (H), and 33.6+/-2.8% (D). There were no significant differences among groups for these parameters. Pooled correlation analyses revealed associations between MCR and IGMV (r=0. 46, P<0.05), MCR and LNV (r=0.44, P<0.05), and IGMV and LNV (r=0.52, P<0.01). This study supports functional coupling between insulin action (both metabolic and vascular) and basal endothelial nitric oxide production in humans.
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PMID:Insulin action is associated with endothelial function in hypertension and type 2 diabetes. 1064 50

Herein are described the development and certain properties of a new drug, pyrazinoylguanidine (PZG), intended for use as an adjunct in the treatment of hypertensive patients with type 2 diabetes, formerly called noninsulin dependent diabetes mellitus. PZG is an analog of the potassium sparing diuretic, amiloride. However, in diabetic patients, amiloride exacerbates hyperglycemia and hyperlipidemia, whereas PZG reduces them. In several studies, PZG not only reduced elevated blood pressure in subjects with essential hypertension, but also downregulated the glucose fatty acid cycle in hypertensive patients with type 2 diabetes. PZG was well tolerated in all patients, as well as in normal subjects whose blood pressures and glucose metabolism were unaffected by PZG. However, in normal subjects made hyperglycemic by giving them hydrochlorothiazide, coadministration of PZG returned blood glucose concentrations to normal. Mechanisms for these effects of PZG in human subjects were investigated in both normal Sprague-Dawley rats and rats made diabetic with streptozotocin (STZ). In isolated rat adipocytes stimulated with theophylline, PZG downregulated both lipolysis and cyclic AMP concentrations. PZG, as well as insulin, increased adipose cyclic nucleotide phosphodiesterase activity, whereas theophylline reduced it. In perfused rat liver, PZG decreased gluconeogenesis and cyclic AMP concentrations. Collectively, these studies illustrate how the side effects (toxicity) of certain drugs, such as the tendency of thiazide diuretics to cause hyperglycemia and hyperlipidemia, can be modulated and even reversed by slight changes in the chemical structure of the molecule, specifically by removal of the 3,5-diamino and 6-chloro substituents on the benzene ring of amiloride to produce PZG.
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PMID:Studies on pyrazinoylguanidine: a novel antihypertensive, hypoglycemic and lipolytic drug intended for adjunctive use in hypertensive patients with type 2 diabetes mellitus. 1078 66


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