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Insulin

About: Insulin is a research topic. Over the lifetime, 124295 publications have been published within this topic receiving 5129734 citations. The topic is also known as: human insulin.


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Journal ArticleDOI
TL;DR: In this paper, the authors investigated whether measurement of plasma HMW adiponectin levels, using a newly developed enzyme-linked immunosorbent assay system for selective measurement of human HMW-derived insulin-sensitizing hormone, may be useful for the prediction of insulin resistance and metabolic syndrome.
Abstract: OBJECTIVE —The high–molecular weight (HMW) form of adiponectin, an adipocyte-derived insulin-sensitizing hormone, has been reported to be the most active form of this hormone. We investigated whether measurement of plasma HMW adiponectin levels, using our newly developed enzyme-linked immunosorbent assay system for selective measurement of human HMW adiponectin level, may be useful for the prediction of insulin resistance and metabolic syndrome. RESEARCH DESIGN AND METHODS —A total of 298 patients admitted for diabetes treatment or coronary angiography served as study subjects. Receiver operator characteristic (ROC) curves for the HMW ratio (HMWR; ratio of plasma level of HMW adiponectin to that of total adiponectin) and plasma total adiponectin levels were plotted to predict the presence of insulin resistance and metabolic syndrome. RESULTS —The area under the ROC curve (AUC) of the HMWR values to predict the presence of insulin resistance was significantly larger than that of plasma total adiponectin level in total subjects (0.713 [95% CI 0.620–0.805] vs. 0.615 [0.522–0.708], P = 0.0160). The AUC for the HMWR values to predict the presence of metabolic syndrome was significantly larger than that for plasma total adiponectin levels in men (0.806 [0.747–0.865] vs. 0.730 [0.660–0.800], P = 0.0025) and in women (0.743 [0.659–0.828] vs. 0.637 [0.532–0.742], P = 0.0458). CONCLUSIONS —The HMWR value has better predictive power for the prediction of insulin resistance and metabolic syndrome than plasma total adiponectin level.

528 citations

Journal ArticleDOI
TL;DR: There is a genuine need for thorough and comprehensive study of the neuropathological changes associated with diabetes mellitus, in the presence of superimposed AD or vascular dementia, and strategies for intervention may depend entirely upon whether the CNS disease processes are mediated by peripheral, central, or both types of insulin resistance.
Abstract: Interest in characterizing the role of impaired insulin actions in Alzheimer's disease (AD) and vascular dementia is growing exponentially. This review details what is currently known about insulin, insulin-like growth factor type I (IGF-I) and IGF-II proteins and their corresponding receptors in the brain, and delineates the major controversies pertaining to alterations in the expression and function of these molecules in AD. The various experimental animal models generated by over-expression, mutation, or depletion of genes that are critical to the insulin or IGF signaling cascades are summarized, noting the degrees to which they reproduce the histopathological, biochemical, molecular, or behavioral abnormalities associated with AD. Although no single model was determined to be truly representative of AD, depletion of the neuronal insulin receptor and intracerebroventricular injection of Streptozotocin reproduce a number of important aspects of AD-type neurodegeneration, and therefore provide supportive evidence that AD may be caused in part by neuronal insulin resistance, i.e. brain diabetes. The extant literature did not resolve whether the CNS insulin resistance in AD represents a local disease process, or complication/extension of peripheral insulin resistance, i.e. chronic hyperglycemia, hyperinsulinemia, and Type 2 diabetes mellitus. The available epidemiological data are largely inconclusive with regard to the contribution of Type 2 diabetes mellitus to cognitive impairment and AD-type neurodegeneration. A major conclusion drawn from this review is that there is a genuine need for thorough and comprehensive study of the neuropathological changes associated with diabetes mellitus, in the presence or absence of superimposed AD or vascular dementia. Strategies for intervention may depend entirely upon whether the CNS disease processes are mediated by peripheral, central, or both types of insulin resistance.

527 citations

Journal ArticleDOI
01 Oct 1997-Diabetes
TL;DR: These results were consistent with more than one independent physiological process underlying risk variable clustering: a central metabolic syndrome (characterized by hyperinsulinemia, dyslipidemia, and obesity), glucose intolerance, and hypertension.
Abstract: Insulin resistance has been hypothesized to unify the clustering of hypertension, glucose intolerance, hyperinsulinemia, increased levels of triglyceride and decreased HDL cholesterol, and central and overall obesity. We tested this hypothesis with factor analysis, a statistical technique that should identify one factor if a single process underlies the clustering of these risk variables. From 2,458 nondiabetic subjects of the Framingham Offspring Study, we collected clinical data, fasting and 2-h postchallenge glucose and insulin levels, and fasting lipid levels. We performed factor analyses separately for men and women in the entire population and among subgroups with features of the insulin resistance syndrome. Subjects ranged in age from 26 to 82 years (mean age 54); 53% were women, 13.4% had impaired glucose tolerance, 27.6% had hypertension, 40% were obese, and 11.6% were hyperinsulinemic, defined by elevated fasting insulin levels. Underlying the clustering of these risk variables were three factors. Fasting and 2-h postchallenge insulin levels, fasting triglyceride and HDL cholesterol levels, BMI, and waist-to-hip ratio were associated with one factor. Fasting and 2-h levels of glucose and insulin were associated with a second factor. Systolic blood pressure, diastolic blood pressure, and BMI were associated with a third factor. Results were similar for men and women and for all subgroups. These results were consistent with more than one independent physiological process underlying risk variable clustering: a central metabolic syndrome (characterized by hyperinsulinemia, dyslipidemia, and obesity), glucose intolerance, and hypertension. Glucose intolerance and hypertension were linked to the central syndrome through shared correlations with insulin levels and obesity. Insulin resistance (reflected by hyperinsulinemia) alone did not appear to underlie all features of the insulin resistance syndrome.

527 citations

Journal ArticleDOI
TL;DR: Activation of the mTOR pathway is increased in liver and muscle of high fat-fed obese rats and in vitro studies with rapamycin suggest that mTOR/S6K1 overactivation contributes to elevated serine phosphorylation of IRS-1, leading to impaired insulin signaling to Akt in liver or muscle of this dietary model of obesity.
Abstract: The mammalian target of rapamycin (mTOR) pathway integrates insulin and nutrient signaling in numerous cell types. Recent studies also suggest that this pathway negatively modulates insulin signaling to phosphatidylinositol 3-kinase/Akt in adipose and muscle cells. However, it is still unclear whether activation of the mTOR pathway is increased in obesity and if it could be involved in the promotion of insulin resistance. In this paper we show that basal (fasting state) activation of mTOR and its downstream target S6K1 is markedly elevated in liver and skeletal muscle of obese rats fed a high fat diet compared with chow-fed, lean controls. Time-course studies also revealed that mTOR and S6K1 activation by insulin was accelerated in tissues of obese rats, in association with increased inhibitory phosphorylation of insulin receptor substrate-1 (IRS-1) on Ser636/Ser639 and impaired Akt activation. The relationship between mTOR/S6K1 overactivation and impaired insulin signaling to Akt was also examined in hepatic cells in vitro. Insulin caused a time-dependent activation of mTOR and S6K1 in HepG2 cells. This was associated with increased IRS-1 phosphorylation on Ser636/Ser639. Inhibition of mTOR/S6K1 by rapamycin blunted insulin-induced Ser636/Ser639 phosphorylation of IRS-1, leading to a rapid (approximately 5 min) and persistent increase in IRS-1-associated phosphatidylinositol 3-kinase activity and Akt phosphorylation. These results show that activation of the mTOR pathway is increased in liver and muscle of high fat-fed obese rats. In vitro studies with rapamycin suggest that mTOR/S6K1 overactivation contributes to elevated serine phosphorylation of IRS-1, leading to impaired insulin signaling to Akt in liver and muscle of this dietary model of obesity.

527 citations

Journal ArticleDOI
TL;DR: Closed-loop glucose control using an external sensor and insulin pump provides a means to achieve near-normal glucose concentrations in youth with type 1 diabetes during the overnight period and the addition of small manual priming bolus doses of insulin improves postprandial glycemic excursions.
Abstract: OBJECTIVE —The most promising β-cell replacement therapy for children with type 1 diabetes is a closed-loop artificial pancreas incorporating continuous glucose sensors and insulin pumps. The Medtronic MiniMed external physiological insulin delivery (ePID) system combines an external pump and sensor with a variable insulin infusion rate algorithm designed to emulate the physiological characteristics of the β-cell. However, delays in insulin absorption associated with the subcutaneous route of delivery inevitably lead to large postprandial glucose excursions. RESEARCH DESIGN AND METHODS —We studied the feasibility of the Medtronic ePID system in youth with type 1 diabetes and hypothesized that small manual premeal “priming” boluses would reduce postprandial excursions during closed-loop control. Seventeen adolescents (aged 15.9 ± 1.6 years; A1C 7.1 ± 0.8%) underwent 34 h of closed-loop control; 8 with full closed-loop (FCL) control and 9 with hybrid closed-loop (HCL) control (premeal priming bolus). RESULTS —Mean glucose levels were 135 ± 45 mg/dl in the HCL group versus 141 ± 55 mg/dl in the FCL group ( P = 0.09); daytime glucose levels averaged 149 ± 47 mg/dl in the HCL group versus 159 ± 59 mg/dl in the FCL group ( P = 0.03). Peak postprandial glucose levels averaged 194 ± 47 mg/dl in the HCL group versus 226 ± 51 mg/dl in the FCL group ( P = 0.04). Nighttime control was similar in both groups (111 ± 27 vs. 112 ± 28 mg/dl). CONCLUSIONS —Closed-loop glucose control using an external sensor and insulin pump provides a means to achieve near-normal glucose concentrations in youth with type 1 diabetes during the overnight period. The addition of small manual priming bolus doses of insulin, given 15 min before meals, improves postprandial glycemic excursions.

527 citations


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Performance
Metrics
No. of papers in the topic in previous years
YearPapers
20243
20232,520
20225,252
20213,164
20203,368
20193,376