Insulin Sensitivity In Healthy Individuals Research Articles

Acute Effect of the Transdermal Administration of Nicotine on Insulin Sensitivity in Healthy Individuals With and Without a Family History of Type 2 Diabetes Mellitus in the First Branch

The aim of this study was to evaluate the acute effect of the transdermal administration of nicotine on insulin sensitivity in healthy individuals with and without family histories of type 2 diabetes mellitus (DM2) in the first branch. A randomized, double-blind, cross-over, placebo-controlled clinical trial with two parallel groups was carried out in 12 healthy individuals, six with a family history of diabetes and six without such family history. The volunteers were randomly assigned to administration of a nicotine or placebo patch and were crossed-over with a difference of at least 3 days between each patch. The insulin sensitivity was estimated by means of the total glucose metabolism, which was obtained with the euglycemic- hyperinsulinemic clamp technique before the randomized assignment and on the following day for the corresponding patch. At the beginning of each clamp technique procedure, the metabolic and hepatic profiles were measured. We found that the total glucose metabolism value was not modified with the administration of nicotine, either in the group with a family history of DM2 (3.9 +/- 1.0 vs. 3.5 +/- 0.7 mg/kg/min; p = 0.60) or in the group without such a family history (5.4 +/- 2.0 vs. 5.1 +/- 1.6 mg/kg/min; p = 0.34). The administration of placebo did not modify the insulin sensitivity in either group. We conclude that acute transdermal administration of nicotine did not modify insulin sensitivity in healthy individuals with or without a family history of DM2 in the first branch.

Relationship between muscle fibre composition, glucose transporter protein 4 and exercise training: possible consequences in non-insulin-dependent diabetes mellitus.

Skeletal muscle is composed of different fibre types, which differ in contractile as well as in metabolic properties. The myosin molecule, which exists in several different isoforms, is of major importance in determining the contractile properties of the muscle cell. The plasticity of skeletal muscle is reflected in this tissue's adaptability to changes in the functional demand. In both rats and humans, a decrease in activity level will in most cases change the muscle fibre composition towards faster myosin isoforms and an increase in activity level (such as seen with exercise training) will induce an increase in slower myosin isoforms. The glucose transporter protein 4 (GLUT4), which is the major insulin regulatable glucose transporter in mammalian skeletal muscle, is found in larger amounts in slow muscle fibres compared with fast muscle fibres. An increase in activity level will increase the GLUT4 protein expression and a decrease in activity level will in most cases decrease GLUT4. Thus, there seems to be some kind of relationship between the muscle fibre type and GLUT4. However, the main factor regulating both the GLUT4 protein expression and the muscle fibre composition seems to be the activity level of the muscle fibre. Patients suffering from non-insulin-dependent diabetes mellitus (NIDDM) are insulin resistant in their skeletal muscles but are generally normal when it comes to skeletal muscle fibre composition and the GLUT4 protein expression. There is good evidence that exercise training beneficially impacts on insulin sensitivity in healthy individuals and in patients with type II diabetes. An increase in the GLUT4 protein expression in skeletal muscle may at least partly explain this effect of training.

Loss of the normal coupling between the anaerobic threshold and insulin sensitivity in chronic heart failure

OBJECTIVETo explore whether the anaerobic threshold, a measure of the balance between aerobic and anaerobic cellular metabolism, is related to whole body insulin sensitivity in healthy individuals and in patients...