Insulin-glucagon interaction in controlling splanchnic glucose production in normal man

Area of Science:

• Endocrinology
• Metabolism

Background:

• Glucagon and insulin are key hormones regulating hepatic glucose production.
• Previous studies inferred their interaction from indirect measurements.

Purpose of the Study:

• To directly examine the interaction of glucagon and insulin in controlling net splanchnic glucose production (NSGP) in humans.
• To determine if insulin can modulate glucagon's effect on glucose production.

Main Methods:

• Infusion of glucagon and insulin into normal men.
• Measurement of arterial hormone levels and NSGP.
• Stabilization of blood glucose using glucose infusions.

Main Results:

• Glucagon infusion alone increased NSGP.
• Exogenous insulin suppressed NSGP and led to net glucose uptake.
• High insulin concentrations (insulin:glucagon molar ratio ~100) blocked glucagon-stimulated NSGP.
• Lower insulin concentrations (ratio ~33) allowed some glucagon stimulation.

Conclusions:

• Insulin, at high concentrations, can effectively suppress glucagon-stimulated hepatic glucose production in normal individuals.
• The insulin:glucagon ratio is a critical factor in regulating glucose homeostasis.