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.

Insulin resistance syndrome in 8-year-old Indian children: small at birth, big at 8 years, or both?

Abstract: We have studied 477 8-year-old Indian children to define the relationship between birth weight and cardiovascular risk factors, including insulin resistance syndrome (IRS) variables and plasma total and LDL cholesterol concentrations. All risk factors were strongly related to current weight. After adjustment for current weight, age, and sex, lower birth weight was associated with higher systolic blood pressure (P = 0.008), fasting plasma insulin and 32-33 split proinsulin concentrations (P = 0.08 and 0.02), glucose and insulin concentrations 30 min postglucose (P = 0.06 and 0.04), subscapular/triceps skinfold ratio (P = 0.003), and plasma total and LDL cholesterol concentrations (P = 0.002 and 0.001). Lower birth weight was associated with increased calculated insulin resistance (homeostasis model assessment [HOMA], P = 0.03), but was not related to the HOMA index of beta-cell function. The highest levels of IRS variables and total and LDL cholesterol were in children of low birth weight but high fat mass at 8 years. Taller height at 8 years predicted higher fasting plasma insulin concentrations, insulin resistance, and plasma total and LDL cholesterol concentrations. The most insulin-resistant children were those who had short parents but had themselves grown tall. Although the implications of our findings in relation to height are unclear, interventions to improve fetal growth and to control obesity in childhood are likely to be important factors in the prevention of cardiovascular disease and IRS in India.

Sirt1 Regulates Insulin Secretion by Repressing UCP2 in Pancreatic b Cells

Abstract: Sir2 and insulin/IGF-1 are the major pathways that impinge upon aging in lower organisms. In Caenorhabditis elegans a possible genetic link between Sir2 and the insulin/IGF-1 pathway has been reported. Here we investigate such a link in mammals. We show that Sirt1 positively regulates insulin secretion in pancreatic b cells. Sirt1 represses the uncoupling protein (UCP) gene UCP2 by binding directly to the UCP2 promoter. In b cell lines in which Sirt1 is reduced by SiRNA, UCP2 levels are elevated and insulin secretion is blunted. The up-regulation of UCP2 is associated with a failure of cells to increase ATP levels after glucose stimulation. Knockdown of UCP2 restores the ability to secrete insulin in cells with reduced Sirt1, showing that UCP2 causes the defect in glucose-stimulated insulin secretion. Food deprivation induces UCP2 in mouse pancreas, which may occur via a reduction in NAD (a derivative of niacin) levels in the pancreas and down-regulation of Sirt1. Sirt1 knockout mice display constitutively high UCP2 expression. Our findings show that Sirt1 regulates UCP2 in b cells to affect insulin secretion.

Dynamics of Insulin Secretion by the Perfused Rat Pancreas

Abstract: The dynamics of insulin release in response to relatively long infusions of glucose were studied in the isolated perfused rat pancreas. Insulin secretion was determined by immunochemical assay of the total portal vein effluent. Histological examination of the perfused pancreases and measurement of oxygen consumption by these tissues indicated that optimal physiological conditions were used. It was observed that, when glucose was infused for a period of approximately 1 hr into a perfused pancreas, there appeared 2 distinctly different phases of insulin release. There was an early, or rapid, release of insulin which subsided within approximately 2 min, followed by a late, or slow release phase which continually increased in rate until termination of the glucose infusion. The contribution of newly synthesized insulin to either phase was determined by comparing the insulin release by normal control preparations to that by preparations which were treated with puromycin. Incorporation of L-valine-14C was used a...

The metabolic syndrome in overweight Hispanic youth and the role of insulin sensitivity.

Abstract: The prevalence of the metabolic syndrome is highest among Hispanic adults. However, studies exploring the metabolic syndrome in overweight Hispanic youth are lacking. Subjects were 126 overweight children (8-13 yr of age) with a family history for type 2 diabetes. The metabolic syndrome was defined as having at least three of the following: abdominal obesity, low high-density lipoprotein (HDL) cholesterol, hypertriglyceridemia, hypertension, and/or impaired glucose tolerance. Insulin sensitivity was determined by the frequently sampled iv glucose tolerance test and minimal modeling. The prevalence of abdominal obesity, low HDL cholesterol, hypertriglyceridemia, systolic and diastolic hypertension, and impaired glucose tolerance was 62, 67, 26, 22, 4, and 27%, respectively. The presence of zero, one, two, or three or more features of the metabolic syndrome was 9, 22, 38, and 30%, respectively. After controlling for body composition, insulin sensitivity was positively related to HDL cholesterol (P < 0.01) and negatively related to triglycerides (P < 0.001) and systolic (P < 0.01) and diastolic blood pressure (P < 0.05). Insulin sensitivity significantly decreased (P < 0.001) as the number of features of the metabolic syndrome increased. In conclusion, overweight Hispanic youth with a family history for type 2 diabetes are at increased risk for cardiovascular disease and type 2 diabetes, and this appears to be due to decreased insulin sensitivity. Improving insulin resistance may be crucial for the prevention of chronic disease in this at-risk population.

The Effects of Rosiglitazone on Insulin Sensitivity, Lipolysis, and Hepatic and Skeletal Muscle Triglyceride Content in Patients With Type 2 Diabetes

Abstract: We examined the effect of three months of rosiglitazone treatment (4 mg b.i.d.) on whole-body insulin sensitivity and in vivo peripheral adipocyte insulin sensitivity as assessed by glycerol release in microdialysis from subcutaneous fat during a two-step (20 and 120 mU.m(-2).min(-1)) hyperinsulinemic-euglycemic clamp in nine type 2 diabetic subjects. In addition, the effects of rosiglitazone on liver and muscle triglyceride content were assessed by (1)H-nuclear magnetic resonance spectroscopy. Rosiglitazone treatment resulted in a 68% (P < 0.002) and a 20% (P < 0.016) improvement in insulin-stimulated glucose metabolism during the low- and high- dosage-insulin clamps, respectively, which was associated with approximately 40% reductions in plasma fatty acid concentration (P < 0.05) and hepatic triglyceride content (P < 0.05). These changes were associated with a 39% increase in extramyocellular lipid content (P < 0.05) and a 52% increase in the sensitivity of peripheral adipocytes to the inhibitory effects of insulin on lipolysis (P = 0.04). In conclusion, these results support the hypothesis that thiazolidinediones enhance insulin sensitivity in patients with type 2 diabetes by promoting increased insulin sensitivity in peripheral adipocytes, which results in lower plasma fatty acid concentrations and a redistribution of intracellular lipid from insulin responsive organs into peripheral adipocytes.