D 6 6 2h2 glucose

Patients arrived at the CRC at 0650 on the day of the clamp test. A primed-continuous infusion {3.6 mg/kg [(free plasma glucose in mg/dL)/90]} of D-[6,6-²H₂] glucose (99% enriched, Cambridge Isotope Laboratories) was started at 0700. At 0855, the somatostatin infusion (0.1 μg · kg BW⁻¹ · min⁻¹) was commenced, simultaneously with infusion of 20 mU · min⁻¹ · m⁻² (low-dose for 2 h, low clamp), followed by 40 mU · min⁻¹ · m⁻² (high-dose for 2 h, high clamp) of short-acting human insulin (Insuman Rapid, Sanofi-Aventis) (36 (link)). Plasma glucose was measured every 5 min and kept constant by a variable intravenous glucose infusion (20% glucose, enriched in D-[6,6-²H₂] glucose). Insulin-stimulated whole-body glucose disposal (M value: expressed as mg · kg BW⁻¹ · min⁻¹) was calculated as described (37 (link)). M/I was calculated as the HEC-derived M value adjusted for the prevailing insulin concentrations during steady-state conditions. For measuring endogenous glucose production (EGP), participants received a 20-min priming bolus [0.36 mg · kg BW⁻¹ · min⁻¹ · fasting plasma glucose (mg/dL)] of D-[6,6-²H₂] glucose (99% enriched in ²H glucose; Cambridge Isotope Laboratories) at −240 min, followed by a continuous infusion (0.036 mg · kg BW⁻¹ · min⁻¹) (25 (link)).

Mice underwent hyperinsulinemic-euglycemic clamps with deuterated glucose to determine whole-body and hepatic insulin sensitivity as described previously [18] (link), [19] (link). In brief, a silicon catheter (Silastic laboratory tubing, Dow Corning, Midland, MI) was placed into the right jugular vein under Isoflurane (CP Pharma, Burgdorf, Germany) anesthesia. Mice were allowed to recover for 4–5 days and fasted for 6 h on the day of the experiment (03:00–09:00a.m.). To assess basal whole-body glucose disposal, D-[6,6-²H₂]glucose (98% enriched; Cambridge Isotope Laboratories, Andover, MA, USA) was infused at a rate of 4 μmol/kg/min for 120 min. The hyperinsulinemic-euglycemic clamp was performed with a primed (40 mU/kg)-continuous infusion (4 mU/kg/min; Huminsulin, Lilly, Giessen, Germany) for 180 min. Euglycemia was maintained by periodically adjusting a variable 20% glucose infusion. D-[6,6-²H₂]glucose was co-infused together with insulin solution (0.4 μmol/kg/min) and variable glucose infusion to obtain stable tracer concentrations during varying glucose infusion rates. Blood samples were taken at 10-min intervals during the last 30 min of basal, and hyperinsulinemic-euglycemic clamps.