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Insulin Resistance clinical trials

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NCT ID: NCT00361751 Completed - Insulin Resistance Clinical Trials

Substrate Cycling in Energy Metabolism

Start date: May 2003
Phase: Phase 2
Study type: Interventional

Insulin resistance and hyperglycemia contribute to negative outcomes in burned patients. We will assess insulin sensitivity in traditional terms of glucose metabolism, and with regard to the responsiveness of both muscle and liver protein metabolism, in severely burned patients. Plasma free fatty acid (FFA) and tissue TG levels will be manipulated via inhibition of peripheral lipolysis with nicotinic acid or activation of plasma lipoprotein lipase activity with heparin, stimulation of tissue fatty acid oxidation and thus reduction of tissue TG with the peroxisome proliferate-activated receptor (PPAR) alpha agonist fenofibrate. Methodological approaches will include stable isotope tracer techniques to quantify kinetic responses of protein, glucose and lipid metabolism in vivo, quantification of intracellular stores of TG and glycogen by means of magnetic resonance spectroscopy (MRS), as well as quantitative analysis of tissue levels of active products of fatty acids, key intermediates of the insulin signaling pathway, glycogen, the enzyme activities of citrate synthase and glycogen synthase and the activity of the muscle mitochondria. These studies will clarify the physiological and clinical significance of the alterations of tissue lipid metabolism that occur after burn injury, thereby forming the basis for new therapeutic approaches not only in this specific clinical condition but in other clinical circumstances in which hepatic and/or muscle TG is elevated. We will investigate the general hypothesis that the accumulation of intracellular TG in liver and muscle either directly causes insulin resistance in those tissues or serves as an indictor of the intracellular accumulation of active fatty acid products, such as fatty acyl CoA and diacylglycerol, which in turn disrupt insulin action. The following specific hypotheses will be investigated: 1. Intracellular TG is elevated in both muscle and liver in severely burned patients. The reduction of the fat in the liver and the insulin resistance will improve clinical outcomes, glucose and protein metabolism. 2. The insulin signaling pathway, as reflected by phosphoinositol-3-kinase (PI3K) and PKC activity, is impaired in tissues with elevated TG. 3. Fatty acids, or their active intracellular products, are the direct inhibitors of insulin action, rather than the tissue TG itself.

NCT ID: NCT00361023 Completed - Type 2 Diabetes Clinical Trials

Effects of Losartan on Insulin Sensitivity and Secretion in Type 2 Diabetes and Nephropathy

Start date: January 2006
Phase: N/A
Study type: Interventional

Angiotensin type-1 receptor (AT1R) blockers (ARBs) have been recognized recently as regulators of glucose and lipid metabolism in adipocytes and adipose tissue.Moreover telmisartan and irbesartan have been recognized recently as regulators of glucose metabolism. For ARB losartan, the results were controversial. To confirm its effect on glucose metabolism, we designed and performed a prospective, randomized and controlled study in subjects with type 2 diabetes and nephropathy.

NCT ID: NCT00351871 Completed - Chronic Hepatitis C Clinical Trials

Influence of Marker of Insulin Resistance Upon Hepatitis C Virus (HCV) Treatment Responses to PEG Intron and Rebetol Therapy

Start date: April 2002
Phase: Phase 4
Study type: Interventional

The objective of this study is to better understand the influence of insulin resistance upon treatment response in hepatitis C virus treated with PEG Intron and Rebetol.

NCT ID: NCT00351546 Completed - Clinical trials for Diabetes Mellitus, Type 2

A Study to Assess the Effects of DPP-4 Inhibition on Insulin Sensitivity in Type 2 Diabetes

Start date: February 2005
Phase: Phase 3
Study type: Interventional

Type 2 diabetes results when the body does not produce enough insulin and/or is unable to properly use the insulin it makes (insulin resistance). This study was undertaken to assess the effects of vildagliptin on insulin sensitivity in people with type 2 diabetes.

NCT ID: NCT00347087 Completed - Clinical trials for Chronic Heart Failure

Effect of Irbesartan on Insulin Sensitivity in Chronic Heart Failure

Start date: July 2004
Phase: Phase 4
Study type: Interventional

To test whether treatment with the angiotensin II receptor antagonist Irbesartan improves insulin sensitivity and metabolic profile in patients with chronic heart failure.

NCT ID: NCT00345436 Completed - Insulin-Resistance Clinical Trials

Exercise in Insulin-Resistant Minority Adolescents

Start date: February 8, 2006
Phase: N/A
Study type: Observational

Insulin resistance, often accompanied by obesity, plays a major role in the development of type 2 diabetes. This phenomenon may be related with the fact that American adolescents are now becoming less physically active in early puberty, explaining the largely pubertal and post-pubertal onset of type 2 diabetes in adolescence. Although regular physical activity has been suggested to attenuate obesity and prevent type 2 diabetes in high-risk children and adolescents, the magnitude of exercise training-induced improvement in the risk factors for type 2 diabetes has been only recently studied in adults and studied very little in pediatric populations. It is clear that exercise, diet, and genetics all contribute to the development of type 2 diabetes in children. However, the few studies that have been done to dissect the relative contributions of these three risk factors have generally used only lipid profiles as the end point. There have been a number of recent advances in our understanding of the molecular basis of type 2 diabetes, particularly, with regards to insulin regulatory pathways modulated by exercise within muscle tissue.

NCT ID: NCT00345033 Completed - Schizophrenia Clinical Trials

Effectiveness of Aripiprazole for Improving Side Effects of Clozapine in the Treatment of People With Schizophrenia

Start date: March 2005
Phase: Phase 4
Study type: Interventional

This study will evaluate the effects of combination treatment with aripiprazole and clozapine on insulin resistance, blood fat levels, and weight gain in people diagnosed with schizophrenia.

NCT ID: NCT00341406 Completed - Obesity Clinical Trials

Fat Cell Size in Insulin Resistance

Start date: September 4, 2003
Phase:
Study type: Observational

This study, conducted at Stanford University in Palo Alto, California, will examine how insulin metabolism and cardiovascular risk are altered in response to weight loss. Insulin is a natural hormone that causes cells to remove glucose (sugar) from the blood. People who are insulin-sensitive remove glucose efficiently. People who are insulin-resistant require more insulin to remove glucose from the blood. Adult volunteers will be recruited for this study through advertisements in local newspapers in communities around Stanford University. Participants will undergo the following tests and procedures: - Insulin sensitivity testing: Before beginning the study, participants will be tested for insulin sensitivity. For the test, two small catheters (plastic tubes) are placed into two veins - one for infusing glucose, insulin, and sandostatin (a drug that blocks insulin secretion from the pancreas), and one for drawing blood samples. The infusions are done over 3 hours. Blood samples are collected before, during, and at the end of the study to measure how well the cells remove glucose from the blood in response to insulin. - Research diet: Participants are assigned to a low-calorie diet tailored to the individual's metabolic rate. The diets contain either 40 or 60 percent of total calories as carbohydrates, 40 or 20 percent as fat, and the rest as protein. People with type 2 diabetes who are taking diabetes medicine with have a diet of 45 to 50 percent carbohydrates, 35 to 40 percent fat, and the rest protein. - Meal profile: Before beginning the diet and after 4 months on the diet, participants are tested for the effects of the various study diets on control of blood sugar and fats. On the day of each test, participants have a physical examination and provide a medical history. Then, a small catheter is placed in a vein. Blood samples are drawn before breakfast and then hourly for up to 8 hours. - Participants who are diabetic are randomly assigned to take one of three diabetes medications - rosiglitazone, glucophage, or a sulfonylurea compound - to help control blood glucose levels. - Magnetic resonance imaging: This diagnostic test uses a strong magnetic field and radio waves to show structural and chemical changes in tissues. During the scan, the participant lies on a table in a narrow cylinder containing a magnetic field, wearing ear plugs to muffle loud knocking and thumping sounds that occur during the scanning process. He or she can speak with a staff member via an intercom system at all times during the procedure. In addition to these procedures, patients may be asked to have a fat cell biopsy. This is done to determine whether insulin-resistant people have fewer fat cells but more fat per cell than insulin-sensitive people. For this test, a small piece of fat tissue is surgically removed, under local anesthetic, from an area of the lower abdomen. With the participant's consent, genetic testing may be done on the fat tissue sample to look for genes that may link central obesity to insulin resistance. Some participants may be asked to be followed for an additional 3 months after completion of the study for a continued weight loss program. The follow-up includes weekly visits for weight measurements and a review of food records.

NCT ID: NCT00340132 Completed - Obesity Clinical Trials

Cross-Sectional and Longitudinal Studies of "Pre-Diabetes" in the Pima Indians

Start date: January 1, 1983
Phase:
Study type: Observational

Insulin resistance and a defect in early insulin secretion are risk factors for the development of type 2 diabetes mellitus. A recent longitudinal analysis which tracked the development of diabetes demonstrated that both insulin action and early insulin secretion deteriorate as individuals progress from normal to impaired glucose tolerance and then to diabetes. These results suggest that both inherent (apparent in normal glucose tolerant subjects who progress to diabetes and likely to have a genetic basis) and acquired (evident as individuals progress from NGT to IGT to diabetes and possibly environmental in origin) defects in insulin action and secretion contribute to the pathogenesis of type 2 diabetes. To identify the genetic and environmental determinants of diabetes we are continuing to determine: (1) if there are genes that segregate with metabolic risk factors for diabetes which might therefore be genetic markers for type 2 diabetes and (2) the mechanisms mediating genetic and environmental determinants of insulin resistance and impaired insulin secretion. <TAB> Volunteers for this study will be admitted to the clinical research ward where they will undergo several tests to determine body composition, oral and intravenous glucose tolerance and in vivo insulin action. In addition, in selected subjects, adipose and/or skeletal muscle tissue will be obtained by percutaneous biopsy for in vitro studies of gene expression and insulin action in these tissues. A transformed lymphocyte cell line will be established for each subject as a permanent source of DNA for genetic studies. Genetic markers for type 2 diabetes and insulin resistance will be sought by typing each individual at positional and functional candidate loci in the hopes of finding an association between these loci and obesity, insulin secretion, insulin resistance and/or type 2 diabetes. ...

NCT ID: NCT00339833 Completed - Diabetes Clinical Trials

The Effects of Anti-Inflammatory Treatment on Insulin Resistance in Healthy Volunteers

Start date: March 2003
Phase: Phase 4
Study type: Interventional

This study, conducted at the Phoenix Indian Medical Center, Phoenix, Arizona, will determine whether reducing subclinical inflammation lessens insulin resistance in healthy, obese volunteers. The study findings may lead to new strategies for preventing type 2 diabetes. In diabetes, blood sugar is higher than normal and can result in serious medical problems, such as blindness and kidney failure. People with subclinical inflammation-inflammation that does not produce symptoms, such as fever, pain, or skin redness-are at increased risk for diabetes. Although the reasons for this are not completely understood, it is known that subclinical inflammation exacerbates insulin resistance, which is a cause of diabetes. Insulin is a hormone that helps control blood sugar, and when it does not work properly, the condition is known as insulin resistance. Normal, healthy volunteers between 18 and 45 years old with a body mass index of at least 30 kg/m2 and who have subclinical inflammation (determined by blood tests) may be eligible for this study. Candidates must be non-smokers and must not have an alcohol or drug problem. Candidates will be screened with a medical history and physical examination, electrocardiogram, and blood and urine tests. Participants will maintain a standard diet and undergo tests and procedures during a 14-day inpatient stay at the Phoenix Indian Medical Center.