All you wanted to know about insulin

  • By Dr. T Deepa Porkodi

When one says diabetes treatment, insulin is one of the many things that come to mind. So what is this insulin? What does it do and where does it come from?

What is insulin?
Insulin is a hormone. It is produced by the pancreas, to be specific by the beta cells in the Islet of Langerhans in the pancreas.

In 1869 Paul Langerhans, a medical student in Berlin found clumps of cells in the pancreas. These were named as ''Islets of Langerhans''. Edouard Laguesse later suggested that they might produce secretions that play a regulatory role in digestion. The term ''insulin'' has its origins from the German word for islet.

What is the use of insulin?
Insulin is needed by the body to metabolise the food that we eat and to absorb the nutrients from it, especially glucose.

What are the specific roles of insulin?

  1. It causes the liver cells, muscles and fat tissue to take the sugar from the blood, convert it to glucagon and store it up for later use.
  2. It stops the body from using fat as a source of energy. The fat is saved as a last minute resort in emergencies like fasting, anorexia etc.
  3. It regulates other body systems.
  4. It has several other anabolic functions as well.

When is insulin secreted?
Insulin is secreted whenever the body needs to metabolise glucose. So, high levels of blood glucose stimulates the pancreas to release insulin. Insulin secretion is also stimulated by the sight, smell and taste of food.

What role does insulin play in diabetes?
In diabetes, one of the two things can happen:

  1. The insulin content secreted is insufficient - this results in type I diabetes. In such cases, the body needs insulin from outside to help utilize the sugar for its energy requirements.
  2. The insulin is secreted in sufficient amounts, but the body is not able to use them - this is called insulin-resistance and is the main pathophysiology of Type II diabetes. In such cases, the patients are give medications to keep sugar levels under control and in severe cases external insulin is needed to keep a check on the sugar levels.

The role of insulin in glucose synthesis is of utmost importance. Even if you lead a healthy lifestyle, you may still fall prey to diabetes if the insulin isn’t working properly or if there is no insulin.

What is insulin, the injection?
The insulin injections are of two types. In earlier days, the insulin produced in the bodies of pigs and cows were used to treat human patients of Type I diabetes. With advances in medical science, the insulin is produced synthetically from genetically engineered bacteria. This has replaced the animal insulin all over the world, except a few countries where the animal version is cheaper.

What are the types in the synthetic insulin?
The synthetically prepared insulin is of various types depending on the strength, the number of doses required, action time and how long the effects last.

  1. Rapid Acting Insulin: Starts working about 5 minutes after injecting it. Its action peaks at 1 hour and the effect stays for 2 to 4 hours.
  2. Regular or Short Acting Insulin: This starts working around 30 minutes after injecting. It peaks after 2 to 3 hours and the effects stay for 3 to 6 hours. This type of insulin is also used intravenously.
  3. Intermediate Insulin: This insulin takes 2 to 4 hours to act, peaks after 4 to 12 hours and stays effective for around 18 hours.
  4. Long-acting insulin: This type of insulin takes 6 to 10 hours after injection to begin acting. It is usually effective for 20 to 24 hours.
  5. Premixed Insulin: This is a combination of two of the above mentioned insulins. The usual combination is of rapid or short acting insulin with intermediate insulin.

What is the strength of the insulin used?
The most commonly used strength is U100 or U40, which means that it has 100 units or 40 units of insulin per milliliter of fluid.

How is insulin administered?
Insulin is usually administered in the injection form. You may also get the pen form which is preloaded with insulin. There are other delivery devices which contain prefilled insulin cartridges that have to be filled into a device.