Endogenous incretin hormone augmentation of acute insulin secretion in normoglycemic relatives of type 2 diabetic subjects: a 10-year retrospective pathophysiological study.

Aims/hypothesis: The pathophysiological role of gut incretin hormone argumentation on acute insulin release in the genesis of type 2 diabetes (TDM2) is uncertain. We examined retrospectively at 0 year and 10 years the endogenous incretin hormone action (IHA) on acute insulin release and glucose tolerance in normoglycemic relatives (REL) of TDM2 and control (CON) subjects.

Methods: At 0 year and 10 years, glucose tolerance, paired oral glucose tolerance test (OGTT)- and i.

The metabolic responses induced by acute dexamethasone predict glucose tolerance and insulin secretion over 10 years in relatives of type 2 diabetic subjects.

Background: This study aimed to compare the metabolic and insulin secretory responses to dexamethasone with the metabolic responses observed at 10 years in normoglycaemic relatives of type 2 diabetic and healthy control subjects.

Methods: Twenty relatives and 20 matched control subjects were studied twice at 0 year (pre- and post-dexamethasone) and at 10 years, employing a 75-g oral glucose tolerance test (OGTT), with serial measurements of glucose and insulin, for determination of glucose tolerance and calculations of acute insulin release (ΔI30 /ΔG30 ; insulinogenic index) and insulin sensitivity (SIHOMA ).

Results: Following dexamethasone, the relatives group developed varying degrees of glucose intolerance, associated with reduced insulin sensitivity and insulinogenic index.

The 4-mg intravenous dexamethasone suppression test in the diagnosis of Cushing's syndrome.

Objective: Optimal diagnostic criteria for the 4-mg intravenous dexamethasone suppression test (IVDST) in patients with Cushing's syndrome (CS), compared with normal subjects, have not been established. We evaluated the performance of the 4-mg IVDST for differentiating CS from normal subjects and to define the responses in CS of various aetiologies. DESIGN, SUBJECTS, MEASUREMENTS: Thirty-two control subjects [normal and overweight/obese participants with or without type 2 diabetes) were prospectively studied, and data from 66 patients with Cushing's disease (CD), three with ectopic ACTH syndrome (EAS), 14 with adrenal Cushing's (AC)] and 15 with low probability of CS (LPC) from three tertiary hospitals were retrospectively evaluated.

Dexamethasone administration inhibits skeletal muscle expression of the androgen receptor and IGF-1--implications for steroid-induced myopathy.

Context: Glucocorticoids are a well-recognized cause of muscle weakness. The early effects of glucocorticoids on skeletal muscle (SkM) androgen and IGF-1 pathways have not been previously investigated in human subjects.

Objective: To determine if administration of the potent glucocorticoid dexamethasone down-regulates SkM androgen receptor and the IGF-1 signalling pathway.

Skeletal muscle 11beta hydroxysteroid dehydrogenase type 1 activity is upregulated following elective abdominal surgery.

Objective: Cortisol has been traditionally implicated in the causation of peri-operative skeletal muscle (SkM) insulin resistance, but cortisol levels return to normal within 72 h of surgery. Tissue cortisol bioactivity may be prolonged by local upregulation of the enzyme 11betaHSD1. We aimed to investigate the changes of SkM 11betaHSD1 enzyme activity and mRNA expression, relative to plasma cortisol, insulin and glucose levels following elective abdominal surgery.

Adiponectin, skeletal muscle adiponectin receptor expression and insulin resistance following dexamethasone.

Objective: Skeletal muscle is a major site of adiponectin action and of glucocorticoid-induced insulin resistance. Little human data exist however, regarding the impact of exogenous glucocorticoids on adiponectin receptors in skeletal muscle.

Design And Patients: Twelve subjects with type 2 diabetes and 12 controls underwent blood sampling and muscle biopsy of vastus lateralis before and after 4 days of 4 mg dexamethasone.

Altered activity of 11beta-hydroxysteroid dehydrogenase types 1 and 2 in skeletal muscle confers metabolic protection in subjects with type 2 diabetes.

Context: There is little information regarding the regulation of 11beta-hydroxysteroid dehydrogenase (11beta-HSD) enzymes in skeletal muscle in the setting of type 2 diabetes.

Objective: Our objective was to investigate whether there is differential mRNA expression and enzyme activity of 11beta-HSD1 and 11beta-HSD2 in the skeletal muscle of diabetic subjects compared with controls at baseline and in response to dexamethasone.

Design: Participants underwent muscle biopsy of vastus lateralis at baseline and after dexamethasone.

11Beta hydroxysteroid dehydrogenase type 1 is expressed and is biologically active in human skeletal muscle.

Objective: No data exist regarding the distribution and oxoreductase enzyme activity of 11beta hydroxysteroid dehydrogenase type 1 (11beta HSD-1) in fresh human skeletal muscle. We aimed to investigate the mRNA and protein expression of 11beta HSD-1 in fresh skeletal muscle, confirm its biological activity and determine its relationship with hexose-6-phosphate dehydrogenase (H6PDH). We also examined the muscle fibre localization of 11beta HSD-1.

Impact of in vivo fatty acid oxidation blockade on glucose turnover and muscle glucose metabolism during low-dose AICAR infusion.

AMPK plays a central role in influencing fuel usage and selection. The aim of this study was to analyze the impact of low-dose AMP analog 5-aminoimidazole-4-carboxamide-1-beta-d-ribosyl monophosphate (ZMP) on whole body glucose turnover and skeletal muscle (SkM) glucose metabolism. Dogs were restudied after prior 48-h fatty acid oxidation (FA(OX)) blockade by methylpalmoxirate (MP; 5 x 12 hourly 10 mg/kg doses).

Do adiponectin, TNFalpha, leptin and CRP relate to insulin resistance in pregnancy? Studies in women with and without gestational diabetes, during and after pregnancy.

Background: The role of adiponectin, tumour necrosis factor alpha (TNFalpha), leptin and C-reactive protein in the insulin resistance of pregnancy is not clear. We measured their levels in women with gestational diabetes (GDM) and in controls, during and after pregnancy, and related them to insulin secretion and action.

Methods: Nineteen women with GDM and 19 BMI-matched healthy pregnant women underwent intravenous glucose tolerance tests in the third trimester of pregnancy and 4 months postpartum to determine insulin sensitivity (SI) and insulin secretion.

Prevailing hyperglycemia is critical in the regulation of glucose metabolism during exercise in poorly controlled alloxan-diabetic dogs.

The separate impacts of the chronic diabetic state and the prevailing hyperglycemia on plasma substrates and hormones, in vivo glucose turnover, and ex vivo skeletal muscle (SkM) during exercise were examined in the same six dogs before alloxan-induced diabetes (prealloxan) and after 4-5 wk of poorly controlled hyperglycemic diabetes (HGD) in the absence and presence of approximately 300-min phlorizin-induced (glycosuria mediated) normoglycemia (NGD). For each treatment state, the approximately 15-h-fasted dog underwent a primed continuous 150-min infusion of [3-(3)H]glucose, followed by a 30-min treadmill exercise test (approximately 65% maximal oxygen capacity), with SkM biopsies taken from the thigh (vastus lateralis) before and after exercise. In the HGD and NGD states, preexercise hepatic glucose production rose by 130 and 160%, and the metabolic clearance rate of glucose (MCRg) fell by 70 and 37%, respectively, compared with the corresponding prealloxan state, but the rates of glucose uptake into peripheral tissues (Rd(tissue)) and total glycolysis (GF) were unchanged, despite an increased availability of plasma free fatty acid in the NGD state.

Skeletal muscle basal AMP-activated protein kinase activity is chronically elevated in alloxan-diabetic dogs: impact of exercise.

The effect of diabetes and exercise on skeletal muscle (SkM) AMP-activated protein kinase (AMPK)alpha1 and -alpha2 activities and site-specific phosphorylation of acetyl-CoA carboxylase was examined in the same six dogs before alloxan (35 mg/kg)-induced diabetes (C) and after 4-5 wk of suboptimally controlled hyperglycemic and hypoinsulinemic diabetes (DHG) in the presence and absence of 300-min phlorizin (50 microg.kg-1.min-1)-induced "normoglycemia" (DNG).