Aims/hypothesis In skeletal muscle, ceramides may be involved in the pathogenesis of insulin resistance through an attenuation of insulin signalling. This study investigated total skeletal muscle ceramide fatty acid content in participants exhibiting a wide range of insulin sensitivities. Methods The middle-aged male participants (n = 33) were matched for lean body mass and divided into four groups: type 2 diabetes (T2D, n = 8), impaired glucose tolerance (IGT, n = 9), healthy controls (CON, n = 8) and endurancetrained (TR, n = 8). A two step (28 and 80 mU m −2 min −1 ) sequential euglycaemic-hyperinsulinaemic clamp was performed for 120 and 90 min for step 1 and step 2, respectively. Muscle biopsies were obtained from vastus lateralis at baseline, and after steps 1 and 2. Results Glucose infusion rates increased in response to insulin infusion, and significant differences were present between groups (T2D

Exercise superimposed on insulin stimulation is shown to increase muscle glucose metabolism and these two stimuli have synergistic effects. The objective of this study was to investigate glucose infusion rates (GIR) in groups with a wide variation in terms of insulin sensitivity during insulin stimulation alone and with superimposed exercise. Patients with type 2 diabetes, subjects with impaired glucose tolerance (IGT), healthy controls, and endurance-trained subjects were studied. The groups were matched for age and lean body mass (LBM), and differed in peak oxygen uptake (VO2 peak), body fat percentage, body mass index (BMI), fasting plasma glucose concentration, and oral glucose-tolerance test (OGTT). Each subject underwent a two-step sequential hyperinsulinemic, euglycemic clamp. During the last 30 min of the 2nd clamp step, subjects exercised on a bicycle at 43% +/- 2% of VO2 peak. In agreement with the OGTT data, the presence of different GIR during insulin stimulation alone demonstrated varying levels of insulin sensitivity between groups. However, the impairment of GIR in IGT observed during insulin stimulation alone was abolished compared to controls when exercise was superimposed on insulin stimulation. Humans with IGT are resistant to insulin-stimulated but not to exercise-induced glucose uptake.

ATBF and bolus mean infusion pressure increased significantly with a wear time of 48 h in Teflon but not in steel catheters. The maximal pressure required to deliver a bolus infusion increased with wear time of a catheter. A higher maximal pressure was required to deliver a bolus infusion through a Teflon than through a steel catheter. We propose that the difference in infusion counter pressure and ATBF between Teflon and steel catheters with wear time may be explained by better biocompatibility of steel than Teflon.