THE ENDOCRINE PANCREAS
The endocrine pancreas produces the hormones insulin and glucagon, which play major roles
in regulating fuel homeostasis in both the fed and fasted states.
Insulin is secreted primarily in response to an increased blood glucose level. Glucagon is
secreted in response to a decreased blood glucose level.
Insulin directs the storage of excess nutrients in the form of glycogen, triacylglycerol and
protein. The major tissue targets of insulin are muscle, liver and adipose tissue. Glucagon
directs the movement of stored nutrients into the bloodstream. Liver is the primary
physiological target of glucagon.
In the fed state, the actions of insulin predominate in tissues and nutrients are stored. In the
fasted state, the actions of glucagon predominate and stored nutrients are mobilized.
Diabetes mellitus (DM) occurs when there is a deficiency in insulin action, as a result of either
impairment in insulin secretion, or impairment in insulin action in its target tissues.
1. Barrett KE, et al. Chapter 24 “Endocrine Functions of the Pancreas & Regulation of
Carbohydrate Metabolism” in Ganong’s Review of Medical Physiology 24th
ed., McGraw-Hill, 2012: 431-
2. Guyton AC, Hall JE. Chapter 78 “Insulin, Glucagon and Diabetes Mellitus” in Textbook of
Medical Physiology 11st
ed., Elsevier Saunders, 2006: 961-976.
3. Lieberman M, Marks AD. Chapter 26 “Basic Concepts in the Regulation of Fuel Metabolism by
Insulin, Glucagon, and Other Hormones” in Marks’s Basic Medical Biochemistry: A Clinical Approach 4th
ed., Lippincott Williams & Wilkins 2013: 473-492.
4. Holt RIG, Hanley NA. Chapter 11 “Overview of Diabetes” in Essential Endocrinology and
ed., Wiley-Blackwell 2012: 238-256.