The pancreas is below & behind the stomach sitting in a bend of the duodenum, which is the first part of the small intestines. There are 2 functional components.
The first is part of the gastrointestinal tract & participates in digesting & processing food. The second is glandular & produces four hormones which modulate the absorption & storage of glucose (sugar).
The digestive part of the pancreas works hard by secreting 50-133 ounces of “pancreatic juices” daily. This juice has 2 major components: 1) water & electrolytes, primarily bicarbonate to maintain an alkaline pH of 7.5-8.5. 2) and 6-12 grams of pancreatic enzymes needed to digest protein, fats & carbohydrates. Zinc deficiency (which is not all that uncommon) compromises the ability of the pancreatic enzymes to function. Vitamin B6 is needed to enhance Zinc absorption.
It’s quite fascinating how it all works. When your stomach stretches with food intake it release a hormone called Gastrin. This in turn signals the pancreas to get to work releasing its’ juices. Just to make sure the pancreas gets the message, when the acid contents of the stomach move into the duodenum , the duodenum also releases a hormone called Secretin. This hormone signals the specific release of the bicarbonate to create the correct pH environment for the pancreatic enzymes. . Then as the food moves on, the small bowel produces a hormone called Pancreazymin which says now is the time to release the enzymes.
The fat digesting enzymes are lipase, phospholipase A & B , & cholesterol esterase. The protein digesting enzymes are trypsin, chymotrypsin, & proteases. The carbohydrate digesting enzymes are amylase, lactase, sucrase , maltase, & phytase.
Poor digestive enzyme production is a not uncommon cause of symptoms. Such enzyme depletion can result from a poor diet since enzyme formation depends upon nutrient precursors, especially amino acids. The resulting low level of enzymes impairs food absorption further decreasing the enzyme formation & maintaining a vicious malabsorptive cycle.
The obvious solution is to improve the diet & to provide pancreatic support with supplemental pancreatic enzymes, or Pancreatin ( from the pancreas of a lamb, pig, or cow) which contains the pancreatic enzymes. Plant based enzymes are also available, although I have not found them to be a effective.
Temporary support may be all that is needed, unless a person has a constitutionally weak pancreas, or other lasting disorders.
We are most familiar with Insulin. The other hormones are Glucagon, Somatostatin, & Pancreatic Polypeptides.
Insulin is essential for life. It reduces blood sugar by stimulating sugar uptake by the cells. It also stimulates amino acid entrance into the cells. It stimulates the formation of gycogen which is the chief storage form of carbohydrates, stored mainly in the liver , muscles, & fat cells. Insulin promotes the synthesis of proteins & promotes growth. It regulates fat metabolism, increases fat formation, maintains fat stores, & inhibits the mobilization of fat from peripheral stores.
Insufficient insulin results in insulin dependent diabetes. Excess insulin can cause the cells to become less sensitive to the insulin & result in adult onset insulin resistant diabetes which is controlled with diet & medications other than insulin. Excess insulin with insulin administration or with insulin resistance can contribute to obesity, high blood pressure, high blood fats & atherosclerotic heart disease.
Insulin release is stimulated by foods, other GI tract hormones, stress hormones, & acetylcholine. Calcium is an important mediator of insulin activity & activates the glucose transport system in the cells. A calcium deficiency will compromise some of the actions of insulin.
Glucagon is not essential to life. It works antagonistically to insulin, by increasing rather than decreasing blood sugar.. It acts as a fuel mobilizer by stimulating glycogen (stored carbohydrate) release from the liver & muscles. It also promotes the formation of glucose from amino acids (protein) when that is needed. Its’ release is stimulated by hypoglycemia & fasting. It stimulates fat metabolism helping to break down fat & promotes the repair of injured tissues. It increases blood potassium, increases oxygen consumption & promotes sodium excretion.
Proteins & amino acids, gastrointestinal hormones, prolonged exercise, stress hormones, & acetylcholine also stimulate its’ release.
Sugar, fatty acids, & hormones suppress its’ release.
Hypoglycemia is a stress state stimulating the output of Glucagon & other hormones to mobilize fuel from the liver & muscles. But this regulatory response to hypoglycemia is impaired in many older people who have impaired ability to maintain glucose balance. Influences are diet, exercise, nutritional status, body fat per cent, hormone levels, medications, & disease.
What I find most commonly is inadequate dietary protein intake & too many refined carbohydrates. Many people have no idea how much protein to eat, nor how much is in what foods. You can determine your daily protein needs by going to http://www.peternielsen.com/nutritio.htm & calculating based upon your weight & activity level. To find the protein content in foods try http://www.nal.usda.gov/fnic/foodcomp/Data/SR15/sr15.html
The Somatostatin acts to reduce both the insulin & glucagon secretion as needed. The Pancreatic Polypepetides are less understood, but are felt to affect Gastrointestinal secretions.
Decreased pancreatic enzyme production can be found on the Comprehensive Stool & Digestive Analysis which several labs do. I like Great Smokies Lab http://www.gsdl.com/.  It is not unusual for to see find chymotrypsin deficiencies & fat malabsorption. Blood sugar is best measured by a 6 hour glucose tolerance test, though that can be grueling. Severe pancreatic disease can be hard to diagnose & is done by symptoms, CAT scans, serum lipase & amylase & other tests as indicated.