Active clinical trials for "Insulin Resistance"

Free fatty acids (FFA) are the main fuel source in a healthy adult heart, since they are responsible for 70-80% of the myocardial ATP production. Plasma FFA and triglycerides (TG) levels are elevated in obesity and diabetes, evoking substrate competition in the heart: the increased availability of lipids will lead to fat accumulation in the heart, which is associated with cardiac insulin resistance and will therefore restrain insulin-stimulated cardiac glucose oxidation. It is shown that a lower myocardial glucose uptake correlates with decreased diastolic function. The benefits of counterbalancing this lipid overload is proven by previous research in pre-diabetes, which showed the reversibility of impaired myocardial substrate metabolism and improvement of function and structure after modest weight loss induced by lifestyle changes. Ciprofibrates are a ligand of the peroxisome proliferator-activated receptor (PPAR) α and are considered to be a major regulator of the lipid metabolism and promote fat oxidative capacity. They are not only effective in normalizing lipid-lipoprotein levels in patients with the metabolic syndrome, but improve also their insulin sensitivity. We therefore hypothesize that ciprofibrate administration in subjects with impaired glucose metabolism (IGM) influence the myocardial substrate metabolism (via the PPARα pathway) and thereby improve myocardial insulin sensivity.

Branched-chain amino acids (BCAA) belong among nutrients strongly linked with insulin sensitivity (IS) measures. Their exact effect on IS appears to be dependent on various conditions that remain to be better defined . The aim of the current study was to investigate effects of chronic increase of BCAA intake on IS in two groups of healthy subjects differing in their basal consumption of BCAA, i.e. vegans and omnivores. Interventional trial was designed where vegans and omnivores were separately interveined with 15 (women) or 20 (men) grams of BCAA daily. Examinations of participants are intended to be done at baseline, after the intervention and wash-out period. Examinations (anthropometry, hyperinsulinaemic-euglycaemic clamp, arginine test) and blood analyses will be performed at baseline, after the intervention and after a 6 month wash-out period. Samples of subcutaneous abdominal adipose tissue (AT) and skeletal muscle (SM, vastus lateralis) obtained before and after the intervention will be used for various analyses (mRNA levels of selected metabolic markers, fatty acid composition, mitochondrial activity).

In addition to its role as the major regulator of glucose uptake into peripheral tissues, the hormone insulin is also a primary regulator of fat storage and fat burning of the body. Mechanistic animal studies have shown that high insulin may be the initial trigger for weight gain and be the proximal cause of obesity. There is currently no quick or non-invasive way of measuring insulin as research and clinical techniques require collection of a blood sample followed by a complicated and costly biochemical assay. The investigators will test the hypothesis that insulin levels can be accurately measured in saliva in humans following meals that elicit high and low blood insulin responses. Findings will help determine if insulin can be use as a valid fluid to track insulin changes in humans.

Disturbances of de novo lipogenesis (DNL) are one of the features of dysfunction of adipose tissue (AT). Disturbances of DNL play a role in development of metabolic complications of obesity. The goal of this project is to investigate novel pathways of DNL regulation. DNL will be studied during nutritional interventions in healthy and obese subjects in exposure to 2-days high carbohydrate diet preceded by a) 2-days fasting b) several weeks´ ketogenic diet. This nutritional protocol creates conditions for the study of prominent changes in DNL: suppression of DNL during fasting or ketogenic diet followed by stimulation during high-carbohydrate diet. Systemic phenotypic features and molecular indices of DNL regulation in AT will be followed during the protocols. Specific attention will be paid to newly reported pathway- hormone sensitive lipase and transcription factor ChREBP. The results will contribute to development of pharmacological approaches in the treatment of metabolic complications of obesity, targeted selectively to AT, without side effects in other tissues.

Obesity and especially type 2 diabetes (T2D) increases the risk of neurocognitive dysfunctions including adverse effects on brain structure and function. Recent evidence from clinical studies have shown that T2D almost doubles the risk for dementia. As the population gets older, age-related chronic diseases, as T2D, become more prevalent. Scientific evidence is emerging that there are several links between metabolic and neurocognitive functions. Impaired insulin action (i.e. insulin resistance), the main hallmark of T2D, has been suggested as a likely shared common pathophysiological mechanism. However, the neural processes that determine how insulin resistance is are connected to the onset and progression of T2D and dementia remain unclear. In this context, the overall aim is to study brain insulin resistance to disentangle age-related and obesity related brain insulin resistance in healthy normal and overweight/obese persons at the age of 20 to 70 years . To this end, the investigators will assess brain insulin action using intranasal insulin/placebo during functional Magnetic Resonance Imaging (fMRI). Additionally, structural changes and cognitive processes will be assessed as secondary variables.

Healthy subjects with low Vitamin D levels will be randomly assigned to either Vitamin D replacement or placebo for a period of 8 weeks. Insulin sensitivity will be measured before and after the intervention, and the changes will be compared between the two groups. This will help us understand if Vitamin D replacement improves insulin sensitivity. Serum Retinol Binding Protein 4 levels will also be measured to see if changes in insulin sensitivity are mediated by RBP4.

The purpose of this study is to evaluate if a supplement containing omega-3 long chain polyunsaturated fatty acids for three months reduce obesity and insulin resistance to obese adolescents if administered together with a hypocaloric diet.

The aim of this study is primarily to investigate the ability of antioxidants found in orange juice (OJ) to improve the serum lipid profile. Overweight or mildly obese men, who are otherwise healthy, but with elevated serum total cholesterol concentration will be recruited. The time commitment for subjects is ~14wks. Subjects will attend the laboratory on 5 occasions after fasting from midnight. The 1st is a medical screening. Laboratory visits 2 & 5 will take ~90min and will be separated by 3 months, during which time subjects will consume 250ml of an orange drink (either OJ or an orange flavoured control drink) once a day. During visits 2 & 5, subjects will have a scan to assess their %body fat using a low-dose x-ray machine, a 20ml blood sample taken and a small sample of fat tissue (about the size of a haricot bean)taken from underneath the skin of the belly. Subjects will record their food intake for 3-days in weeks 3, 7 and 11 of consuming the drink, and come to the lab for visits 3&4 during weeks 4&8. Laboratory visits 3&4 repeat measurements taken in the 1st (screening) visit.

Experimental elevation of non-esterified fatty acids (NEFA) impairs endothelial function and insulin sensitivity but the impact of NEFA composition is unknown. The objective was to test the effect of acute elevation of NEFA enriched with either saturated fatty acids (SFA) or SFA with long-chain n-3 polyunsaturated fatty acids (LC n-3 PUFA) on postprandial vascular function measured via flow-mediated dilatation (FMD), laser Doppler iontophoresis (LDI) and digital volume pulse (DVP), followed by a hyperinsulinaemic-euglycaemic clamp as a measure of whole body insulin sensitivity.

Obesity has a greater detrimental impact on the health of African American women than on any other racial or gender group. Nearly 80% of African American women are overweight or obese in the United States. Hypertension and insulin resistance are more prevalent among African American women as compared to men and Caucasians. These conditions put them at increased risk for the development of diabetes mellitus and cardiovascular disease. Recent studies have reported that a substance named Nitric Oxide (NO)may have some beneficial effect on how the body handles blood sugar and blood pressure. Of interest,some studies have shown that African Americans have decreased function of NO in their blood vessels. In this study proposal the investigators will test if increasing NO function with a PDE-5 inhibitor (sildenafil citrate) will improve pre-diabetes and the health of the inner layer of the blood vessels in obese African American women.