title: Deciphering the Hypoglycemic Glucagon Response: Development of a Graded Hyperinsulinemic Hypoglycemic Clamp Technique in Female Mice.
abstract: Glucose lowering therapy in type 1 and type 2 diabetes is often associated with hypoglycemic events. To avoid this, glucose lowering therapies need to be developed that support the hypoglycemic defense mechanisms. Such development needs a tool for evaluating counterregulatory mechanisms in vivo. A sustained glucagon release during hypoglycemia is of most importance to hypoglycemic defense mechanisms. We have therefore developed a graded hyperinsulinemic hypoglycemic clamp in mice and used it to evaluate counterregulatory glucagon dynamics. Glucose was clamped at narrow intervals aiming at 2.5, 3.5, 4.5, and 6.0 mmol/L. Glucagon levels were increased during hypoglycemia in a glucose-dependent way with a glucagon counterregulatory threshold between 3.5 and 4.0 mmol/L. Modelling the glucose-glucagon relationship using a hyperbolic curve with the equation: plasma glucagon = -4.20 + 90.79/blood glucose showed high correlation. When comparing this method to the insulin tolerance test as an approach to study glucagon dynamics in vivo, we found that the graded clamp more efficiently evoked a robust, predictable, glucagon response with considerably less variation in blood glucose. In conclusion, we have developed a tool for the study of in vivo glucagon dynamics during hypoglycemia in mice and demonstrated a hyperbolic glucose-counterregulatory glucagon relationship.
authors.affiliation: Department of Clinical Sciences, Lund, Medicine, Lund University, SE-221 84 Lund, Sweden.
authors.forename: Siri
authors.initials: S
authors.lastname: Malmgren
authors.affiliation: Department of Clinical Sciences, Lund, Medicine, Lund University, SE-221 84 Lund, Sweden.
authors.forename: Bo
authors.initials: B
authors.lastname: Ahrén
mesh_terms: D000818:Animals; D001786:Blood Glucose / Q000378:metabolism*; D003920:Diabetes Mellitus / Q000097:blood / Q000175:diagnosis / Q000517:prevention & control; D005260:Female; D005934:Glucagon / Q000097:blood / Q000378:metabolism*; D015309:Glucose Clamp Technique / Q000379:methods*; D006946:Hyperinsulinism / Q000097:blood / Q000378:metabolism; D007003:Hypoglycemia / Q000097:blood / Q000378:metabolism; D007004:Hypoglycemic Agents / Q000494:pharmacology; D007328:Insulin / Q000097:blood / Q000378:metabolism* / Q000494:pharmacology; D000078790:Insulin Secretion; D008810:Mice, Inbred C57BL; D015203:Reproducibility of Results
chemical_list: D001786:Blood Glucose; D007004:Hypoglycemic Agents; D007328:Insulin; D005934:Glucagon