Glucagon has the opposite effect to insulin on the
liver cells and through a complex chain of enzyme
activation degrades the stored glycogen to release
glucose. It only takes a few minutes for serum blood
glucose levels to double. In only four hours, all the
stores in the liver can be degraded. This is why an
increased glucagon production is so dangerous and
hyperglycaemia results. Glucose exerts a high osmotic
pressure in extracellular fluid, leading to cellular
dehydration and system dehydration secondary to
osmotic diuresis by the kidneys.