Insulin: how it is manufactured and works, comorbidities


Insulin is a hormone produced by the pancreas that helps metabolize food and use it for energy throughout the body. This is a key biological function and an insulin problem can have widespread implications for any or all of your tissues, organs, and systems.

Insulin is critical to your overall health and even to your survival. Problems with insulin production or function can lead to hypoglycemia (low blood sugar), hyperglycemia (high blood sugar), and diabetes .

Get Medical Information / Ellen Lindner

If you have any type of diabetes, studying how insulin works in your body can help you understand why taking daily insulin injections , wearing an insulin pump or a patch can be a key aspect of your treatment plan.

This article looks at the relationship between insulin, blood sugar (glucose) levels, and diabetes. It also explains how your body produces insulin and how it can affect your health if there is too little or too much insulin in your bloodstream.

How is insulin produced?

Insulin is produced by the pancreas, a gland-like organ located in the curve of the duodenum (the first part of the small intestine ) just behind the stomach. The pancreas functions as an exocrine gland and also as an endocrine gland .


The exocrine function of the pancreas is to aid digestion . The endocrine function of the pancreas is to produce insulin and another hormone called glucagon, which helps regulate blood sugar levels. The cells of the pancreas that produce glucagon are called alpha cells.

Insulin is produced by specialized beta cells in the pancreas, which are grouped into groups called islets of Langerhans, or islets for short. The pancreas of a healthy adult has approximately one million islets, which occupy approximately 5% of the entire organ.

How does insulin work?

Insulin is an energy storage hormone. After a meal, it helps cells use carbohydrates, fats, and proteins as needed, and store what is left (mostly as fat) for future use. The body breaks these nutrients down into sugar molecules, amino acid molecules, and lipid molecules, respectively. The body also stores and assembles these molecules in more complex ways.

Carbohydrate metabolism

Blood sugar rises when most foods are consumed, but rises more quickly and dramatically with carbohydrates . The digestive system releases glucose from food, and glucose molecules are absorbed into the bloodstream. Increased glucose levels signal the pancreas to secrete insulin to remove glucose from the bloodstream.

To do this, insulin binds to insulin receptors on the surface of cells, acting as a key that opens cells to accept glucose. Insulin receptors are found in almost every tissue in the body, including muscle and fat cells.

Insulin helps transport glucose from the bloodstream via glucose transporters.

Insulin receptors have two main components: the outer part and the inner part. The outer part extends outside the cell and binds to insulin. The inside of the receptor signals the cell to send special proteins called glucose transporters, which absorb and transport glucose around the cell. As blood sugar and insulin levels drop, the receptors are emptied and glucose transporters return to the cell.

When the body functions normally, glucose derived from ingested carbohydrates is rapidly excreted through this process. However, in the absence of insulin or very low insulin levels, this does not happen, resulting in high blood glucose levels.

Too much sugar in the blood also occurs when cells cannot use insulin properly. Insulin resistance can be caused by a problem with the form of insulin (which prevents the receptor from binding), a lack of insulin receptors, problems with signaling, or a malfunction of glucose transporters. Also, insulin resistance can result from excess body fat.

Fat metabolism

Insulin has a great effect on fat metabolism. After a meal, insulin causes the "extra" ingested fat and glucose to be stored as fat for future use. Insulin also plays a key role in liver and fat cell function.

Liver function

Insulin stimulates the production of glycogen from glucose and its storage in the liver. High insulin levels lead to saturation of the liver with glycogen. When this happens, the liver becomes unable to store more.

Instead, glucose is used to create fatty acids, which are converted to lipoproteins and released into the bloodstream. They break down into free fatty acids and are used in other tissues. Some tissues use them to create triglycerides .

Fat cells

Insulin stops the breakdown of fats and prevents the breakdown of triglycerides into fatty acids. When glucose enters these fat cells, it can be used to create a compound called glycerin.

Glycerin can combine with excess free fatty acids from the liver to form triglycerides. This can cause triglycerides to build up in fat cells.

Protein metabolism

Insulin helps amino acids from protein get into cells. Without adequate insulin production, this process is difficult, making it difficult to build muscle.

Insulin also makes cells more susceptible to potassium , magnesium , and phosphate . These minerals, known as electrolytes , help conduct electricity in the body. In addition, they affect:

  • Muscle function
  • Acidity of the blood
  • The amount of water in the body

Electrolyte imbalances can be exacerbated by high blood sugar levels, as this can lead to excessive urination ( polyuria ), causing you to lose more water and electrolytes.


Insulin production is part of an endocrine process in the liver that controls blood sugar levels. Insulin helps the body break down fats, carbohydrates, and proteins in food so they can be used for energy. Insulin resistance develops when the muscles, fat, and cells of the liver cannot use insulin properly, resulting in high blood sugar levels.

Related conditions

Several conditions are associated with problems with the use or production of insulin, including diabetes, hypoglycemia, and hyperglycemia.


Diabetes comes in three forms, each with different causes of high blood sugar.

  • Type 1 diabetes : an autoimmune disease in which the pancreas stops producing insulin. An insulin supplement is required for treatment. This chronic disease usually begins in childhood.
  • Type 2 diabetes : causes insufficient insulin production and / or insulin resistance . Treatment may include insulin supplements, dietary changes, regular exercise, and medication. This chronic disease usually begins in adulthood.
  • Gestational Diabetes : Temporary insulin resistance caused by pregnancy hormones that resolves after pregnancy ends. Treatment may include insulin supplements, dietary changes, and regular exercise.


Hypoglycemia is low blood sugar. People with diabetes are especially susceptible, but it can also happen to people without diabetes. Hypoglycemia is a potentially dangerous condition with symptoms such as:

  • Instability
  • Perspiration
  • Hunger
  • Headache
  • Blurry vision
  • Drowsiness
  • Dizziness
  • Confusion or disorientation
  • Irritability
  • Combat ability
  • Difficult to focus
  • Soft spot
  • Arrhythmia

More serious symptoms of hypoglycemia:

  • Inability to eat or drink
  • Seizures or convulsions
  • Unconscious

Hypoglycemia is often a side effect of diabetes medications , especially those classified as sulfonylureas and meglitinides. The risk of hypoglycemia with these drugs increases if:

  • Eat significantly less than usual
  • Get significantly more physical activity than usual
  • Drinking too much alcohol without eating enough
  • To get sick

Checking your blood sugar frequently, following your diet and exercise regimen can help you avoid diabetes-related hypoglycemia.

Other causes of hypoglycemia include:

  • Indigestion due to stomach surgery or rare enzyme deficiencies.
  • Medications including aspirin , sulfa antibiotics, pentamidine, and quinine.
  • Drunkenness
  • Severe liver, kidney, or heart disease.
  • Low hormone levels, including cortisol , glucagon, adrenaline , or growth hormone
  • Pancreatic tumors


Hyperglycemia is high blood sugar. The most common cause of hyperglycemia is diabetes, but in addition to diabetes, it can be caused by:

  • Infections
  • Certain medications
  • Hormonal imbalance
  • Serious diseases

Symptoms of hyperglycemia include:

  • Increased hunger and / or thirst.
  • Blurry vision
  • Frequent urination
  • Headache
  • Fatigue
  • Involuntary weight loss
  • Vaginal infections
  • Skin infections
  • Slow wound healing

In a person with type 1 diabetes, hyperglycemia can lead to a life-threatening condition called ketoacidosis , in which toxic acids build up in the blood. Symptoms of ketoacidosis include:

  • Threw up
  • Dehydration
  • Fruity-scented breath
  • Difficulty breathing or hyperventilation
  • Fast heartbeat
  • Disorientation, confusion
  • Eat

Untreated hyperglycemia can lead to a variety of problems, including:

  • The nerves are damaged, increasing the risk of vision problems, kidney disease, and healing problems.
  • Damaged blood vessels that increase the risk of heart attack and stroke.
  • Damage to other organs and tissues.


Diabetes, hypoglycemia, and hyperglycemia are conditions related to how much insulin your body makes and how well you use it to control blood sugar levels. Hypoglycemia and hyperglycemia are common in diabetes, but non-diabetic people can develop underlying conditions that affect insulin.


The pancreas has two key roles: the exocrine function, which is responsible for digestion, and the endocrine function, which produces insulin. Your body needs insulin to keep your blood sugar from getting too high or too low. It also allows your liver, muscles, and fat cells to absorb sugar from the food you eat and use it for energy.

If your body doesn't make the proper amount of insulin or doesn't use insulin efficiently, you can develop health problems like diabetes, hyperglycemia, or hypoglycemia. If left untreated, these conditions can be very dangerous and may require lifelong treatment.

Get the word of drug information

Insulin resistance in type 1 diabetes is incurable, but can be controlled with additional insulin . For others, there are ways to prevent the insulin problems that can lead to type 2 diabetes, such as eating a balanced, nutrient-rich diet, maintaining a healthy weight, exercising regularly, and quitting cigarette smoking.

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