Insulin - The Sugar Police

As I mentioned in a previous blog, Glucose - Ah, Sugar Sugar!, man does not live by cheesecake alone. Our cells can only get energy from glucose. Glucose is absorbed directly from the intestines or is created in the body from the foods we eat. It is primarily generated by a breakdown of simple sugars or carbohydrates but can be formed by other pathways. But glucose cannot be absorbed directly into our cells without the help of Insulin.

Insulin is a proteinaceous hormone secreted by a special group of cells in the pancreas called the islets of Langerhans. The pancreas also releases other hormones as well as digestive enzymes, which are released into the intestinal tract and help with the breakdown and absorption of proteins and fats. Insulin controls the level of glucose in our blood and permits cells to absorb and utilize glucose. You can eat lots of food but be in a state of starvation without the action of insulin. As carbohydrates are absorbed into the bloodstream after a meal, insulin is secreted in response to the increased blood sugar. The insulin then attaches to cell receptors where it enhances the absorption of the glucose into the cells. The cells use the glucose for energy or convert it to glycogen for storage. The level of glucose in the blood is thus reduced and maintained at an appropriate level to support bodily functions.

---

You can eat lots of food but be starving without insulin

---

The beta cells in the islets of Langerhans release insulin in two phases. The first phase releases insulin rapidly in response to increased blood glucose levels. The second phase is a sustained, slow release of insulin triggered independently of blood sugar levels. If too much insulin is produced and blood glucose levels drop too low a release of hyperglycemic hormones (mostly notably glucagon from the islet of Langerhans' alpha cells) stimulates the release of glucose into the blood, primarily from glycogen stored in the liver. If we do not produce enough insulin, the sugar stays in our bloodstream and is unable to nourish our cells.


Insulin - Created by Isaac Yonemoto

Insulin is composed of two peptide chains referred to as the A and B chains. These two chains are linked together by two disulfide bonds. In humans, the A chain consists of 21 amino acids and the B chain of 30 amino acids. Within vertebrates, the amino acid sequence of insulin is extremely well-preserved. Bovine (beef) insulin differs from human in only three amino acid residues, and porcine (pork) insulin differs in only one. Even insulin from some species of fish is similar enough to human to be clinically effective.

The actions of insulin on our cells include (partial list):

• Increased glycogen synthesis – increased storage of glucose in the liver and muscles
  
• Increased lipid synthesis – fat cells take in blood lipids, converting them to triglycerides
  
• Decreased proteolysis – decreased protein breakdown
  
• Decreased lipolysis – reduced conversion of fat cell lipids into blood fatty acids
  
• Decreased gluconeogenesis – decreased production of glucose from non-sugar substrates
  
• Increased amino acid uptake – increased absorption of circulating amino acids
  
• Increased potassium uptake – increased absorption of serum potassium
  

As you can see insulin helps regulate many bodily functions beyond just blood sugar. But insulin is probably best known for the disease where we do not have enough - Diabetes. I am sure all of you have heard of Diabetes. It is a disease where we do not produce enough insulin or our bodies resist the insulin we do produce. This lack of insulin activity is why diabetics have high blood sugar. We will take a closer look at how insulin is used in the treatment of Diabetes in a future blog.

Proverbs 25:27 - "It's not good to eat too much honey, and it's not good to seek honors for yourself. (NLT)"