Effect of Breathing Maneuvers on Peripheral Glucose Metabolism
Vagus Nerve StimulationInsulin Sensitivity1 moreTwo important mechanisms play a major role in the pathogenesis of type 2 diabetes: insulin resistance of the target tissues and the impaired insulin secretion from pancreatic β-cells. Postprandial factors (such as insulin) are perceived by the human brain and induce signals that regulate glucose metabolism via the parasympathetic nervous system. Deep breathing exercise can increase parasympathetic nerve activity. Heart rate variability (HRV) in healthy people can be significantly increased by deep breathing maneuvers, indicating a shift from sympathetic activity to parasympathetic activity. The hypothesis is that this postprandial shift results in a change in peripheral glucose metabolism. In turn, the increased parasympathetic activity could potentially result in a change in postprandial insulin sensitivity or secretion. To test this hypothesis, this study investigates the effect of deep breathing exercise versus normal breathing on insulin sensitivity, on insulin secretion, glucose tolerance, resting energy expenditure, and on parasympathetic tone (analysis of heart rate variability).
Effects of Transcutaneous Auricular Vagus Nerve Stimulation on Obesity and Insulin Resistance
Diabetes MellitusType 21 moreBeing overweight or obese has been associated with insulin resistance contributing to an increased risk for the development of type II diabetes. Food intake, metabolic rate, and blood glucose levels are regulated by the autonomic nervous system, including the vagus nerve. This study evaluates the hypothesis that non-invasive transcutaneous auricular vagus nerve stimulation (taVNS) affects hormones that regulate food intake and blood glucose levels in a way that is consistent with reduced food intake and lower blood glucose levels. The investigators further hypothesize that these effects of taVNS depend on body weight. In a cross-over design generally healthy study participants will receive either taVNS or a sham intervention for 30 minutes on two separate study days. The order of the intervention on the two study days will be randomized and the two study days are at least one week apart. Based on body mass index (BMI) study participants are assigned to either a normal weight (BMI<25), overweight (BMI<30), or obese (BMI>30) group. Capillary blood samples taken by finger prick before and after the intervention on each study day will be analyzed for blood glucose concentration and hormones that are linked to food intake and blood glucose levels. In addition, autonomic function will be assessed by heart rate variability analysis of ECG recordings obtained before, during, and after the intervention on each study day.
Exercise to Restore 24h Rhythms in Metabolism
Diabetes MellitusType 21 moreThis study will investigate the effect of exercise training on 24h rhythms in substrate metabolism in overweight subjects with impaired glucose tolerance. Subjects will perform exercise training for 12 weeks. Before and after the exercise period, they will be admitted to research facilities for 45 hours to assess 24h rhythms in substrate metabolism. In a single-arm longitudinal design, subjects will serve as their own control.
Modulation of Insulin Sensitivity by Betaine Upregulation of FGF21
Insulin SensitivityPeople with poor insulin sensitivity do not respond normally to elevations in blood sugar. This may increase their risk of developing diabetes in the future. The purpose of this research study is to determine if the nutrient betaine, found in beets, spinach and wheat products, can enhance the production of fetal growth factor 21 (FGF21), a molecule that is believed to promote insulin sensitivity.
Effect of Reducing Uric Acid on Insulin Sensitivity and Oxidative Status
ObesityMetabolic Syndrome1 moreThe purpose of this study is to learn more about what is the effect of uric acid on oxidative stress and on the way the body metabolizes sugar in obese people. Understanding this may lead to better diseases such as diabetes.
Metformin's Effect on Glucagon-induced Glucose Production and Protein Metabolism.
Insulin ResistancePrediabetic StateThis study is being done to understand metformin's mechanisms of action regarding glucose production, protein metabolism, and mitochondrial function.
Aldosterone, Microvascular Function and Salt-sensitivity
Abdominal ObesityMetabolic Syndrome3 moreCurrently, the incidence of obesity and obesity-related disorders is reaching epidemic proportions, which entails an increasing burden for health care systems. The association of obesity with other risk factors for type 2 diabetes mellitus and cardiovascular disease, such as insulin resistance and hypertension, is often referred to as the metabolic syndrome. During recent years, salt-sensitivity of blood pressure has emerged as an additional cardiovascular risk factor that is related to obesity and other key components of the metabolic syndrome. The underlying pathophysiological mechanisms of these interrelationships are complex and incompletely elucidated. Microvascular dysfunction has been proposed as a link between insulin resistance and hypertension in obese individuals. In addition, impairment of microvascular function was found to be associated with salt-sensitivity of blood pressure. Increased aldosterone levels, as observed in obese individuals, might be a cause of microvascular dysfunction-induced salt-sensitivity and insulin resistance. Aldosterone not only gives rise to sodium-retention in the distal tubule of the kidney, but was also found to impair endothelial function and thus lower NO-availability, which is characteristic of microvascular dysfunction. In addition, elevated aldosterone levels are associated with both hypertension and insulin resistance, which is illustrated in patients with primary aldosteronism, but also in the general population. The investigators hypothesize that increased aldosterone levels in obese individuals lead to impairment of microvascular function through reduction of NO-availability. This microvascular dysfunction is suggested to play a central role in the pathogenesis of salt-sensitive hypertension and insulin resistance.
Acute Effects of an Oral Fat Load on Skeletal Muscle and Hepatic Insulin Sensitivity
Insulin SensitivityThe development of type 2 diabetes is based on a combination of insulin resistance and beta cell dysfunction. In the last years, elevated FFA were recognized as a key players in the pathogenesis of insulin resistance and type 2 diabetes. The study compares the acute effects of an oral lipid bolus on insulin sensitivity and hepatic glucose metabolism in healthy humans.
The Metabolic Effects of a High Fructose Versus a High Glucose Diet in Overweight Men
Hepatic Fatty Acid MetabolismSystemic Insulin Resistance2 moreDietary consumption of fructose has increased by nearly 50% since 1960. A high fructose diet (HFrD) results in greater visceral adiposity and systemic insulin resistance than a high glucose diet. The effects of fructose on liver fatty acid and ATP stores, systemic oxidative stress and cardiovascular status are not fully known.
Effects of Exercise Behavior Modification on Plasma Adiponectin and Insulin Resistance in High Risk...
Diabetes MellitusInvestigators hypothesized home-based exercise intervention was beneficial to those who have had diabetic risk factor for type 2 diabetes mellitus