Glucagon metabolism in humans is poorly understood and is currently under active investigation. We have recently developed a new isotope dilution method using nonradioactive, stable human glucagon (Phe 6 13C9, 15N; Phe 22 13C9, 15N) tracer to measure glucagon fluxes. To estimate postprandial glucagon turnover using this novel technique, we present data from the first 5 healthy subjects (3 males, age 26.2±7.9 years, BMI 25.4±2.6 kg/m2, fasting plasma glucose 4.7±0.2 mM, HbA1c 5.1±0.2 %) done thus far. After IRB approval and informed consent, subjects presented to the clinical research unit in the morning after an overnight fast. A catheter was inserted in a forearm vein for glucagon tracer infusion and another catheter placed in the contralateral hand and the hand kept in a heated box for periodic draws of arterialized venous samples for measurements of glucagon tracer (tandem mass spectrometry), glucagon and glucose concentrations during the study. A mixed meal (75 grams carb, 15% protein, 35% fat; 8 kcal/kg) was ingested at time 0 and the glucagon tracer infusion rate adjusted to mimic the anticipated changes in postprandial circulating glucagon concentrations for 6 hours. Systemic glucagon appearance rate (Ra glucagon) was calculated by the isotope dilution method. Fig 1 shows the Ra glucagon in all subjects. These initial data show that postprandial glucagon turnover can be calculated in humans applying this novel technique.
F. Ruchi: None. Y.R. Yadav: None. D. Romeres: None. S. Sawleh: None. L.M. Benson: None. K.L. Johnson: None. M. Schiavon: None. C. Dalla Man: Research Support; Self; Sanofi-Aventis Deutschland GmbH. C. Cobelli: None. D.J. McCormick: None. R. Basu: Consultant; Self; GENFIT. Research Support; Self; AstraZeneca. A. Basu: Consultant; Spouse/Partner; GENFIT. Research Support; Spouse/Partner; AstraZeneca.
National Institutes of Health (R01DK029953 to R.B.), (R01DK085516 to A.B.), (DK059637, DK020593)