Insulin

Insulin is a hormone produced by the pancreas. Insulin regulates blood glucose or blood sugar levels in the bodies of humans and many other mammals. A pancreas that fails to produce enough insulin or when the body does not respond to the insulin being produced is the main cause of diabetes mellitus. People with diabetes are often prescribed periodic insulin injections to regulate their blood sugar, which reduces or eliminates their symptoms. They may also be required to follow a strict diet to assist with stabilizing insulin levels. Although diabetes is a manageable condition, it has no cure.

Background

Prior to the discovery of insulin, the medical community considered diabetes a terminal condition. Physicians understood that diabetes resulted from a malfunctioning pancreas, but they had no way to effectively treat the condition. While diabetes patients followed a strict, low-sugar diet to combat the disease, diet alone was not particularly effective at extending their life spans.

In 1869, German medical student Paul Langerhans discovered insulin-producing cells in the pancreas. Although he did not understand the function of these cells at the time, they were later named “islets of Langerhans” in his honor. Twenty years later, German physicians Oskar Minkowski and Joseph von Mering discovered that the pancreas created a substance that regulates blood sugar.

In 1920, Canadian pharmacologist Frederick Banting first theorized that a substance to regulate blood sugar could be extracted from the pancreas of a dog. Upon further testing, Banting proved that this extract could be used to keep diabetic animals alive and healthy, even upon removal of the pancreas. This substance was later called insulin.

After learning to purify insulin extracted from the pancreases of cows, Banting and his team began testing on diabetic human volunteers. The tests were resounding successes. Diabetic patients quickly regained their health. As long as they were given carefully measured insulin injections, they could lead normal lives. As credit for his discovery, Banting received the 1923 Nobel Prize in physiology or medicine.

Overview

Diabetes mellitus, often simply called diabetes, refers to a group of disorders that affect the pancreas’s ability to regulate blood sugar. In a healthy person, the pancreas creates insulin and pushes it into the bloodstream. The insulin then spreads throughout the body, triggering chemical reactions in cells that allow blood sugar to enter them. As a result, the amount of blood sugar in the bloodstream decreases. Once the body’s blood sugar reaches the appropriate level, the pancreas stops producing insulin.

Blood sugar is the body’s main source of fuel for muscles, tissue, and the brain. Without blood sugar, bodily cells would be unable to produce energy. With too much blood sugar, they may cease to function. Common symptoms of diabetes include weight loss, hunger, excessive thirst, frequent urination, fatigue, irritability, blurred vision, impaired healing, and the presence of ketones in urine. Over time, diabetes may cause a variety of serious complications. These include nerve damage, kidney damage, blindness, skin conditions, and hearing impairment.

Doctors recognize several variants of diabetes, each of which has specific causes and symptoms. In type 1 diabetes, the body’s own immune system malfunctions. It attacks the insulin-producing cells in the pancreas, which quickly cease to function. Without insulin to regulate the amount of blood sugar in the bloodstream, the body’s blood sugar can rise to dangerous levels. While the medical community is undecided on the exact cause of type 1 diabetes, most believe that certain individuals are genetically predisposed to the disease. Others believe that yet undiscovered environmental factors play a part. The onset of symptoms of type 1 diabetes is often sudden and powerful.

In type 2 diabetes, the body’s cells eventually develop a resistance to insulin. In this scenario, the pancreas continues to produce insulin. However, it cannot produce enough insulin to properly lower the body’s blood sugar levels. The body’s resistance to insulin grows over time, slowly increasing the severity of the disease’s symptoms. Type 2 diabetes is often preceded by prediabetes, which is considered a separate condition. While prediabetes can often be reversed with lifestyle changes, type 2 diabetes has to be managed for the rest of a person’s life. Being overweight or inactive greatly increases the likelihood of developing prediabetes or type 2 diabetes. Both diseases become more common as age increases.

Gestational diabetes occurs during pregnancy. During a normal pregnancy, the placenta produces hormones that increase cellular resistance to insulin. In most cases, the pancreas increases insulin production to compensate for this new resistance. When it cannot, the pregnant person may develop gestational diabetes. Gestational diabetes increases the risk of developing prediabetes and type 2 diabetes later in life.

All people with type 1 diabetes are prescribed insulin therapy to manage their symptoms. Many people with other types of diabetes are also prescribed insulin therapy. If their symptoms are not severe, however, they may be able to manage their disease through lifestyle changes and blood sugar monitoring alone.

Insulin therapy involves injecting insulin into the body using one of several common methods. Insulin may be periodically injected with a hypodermic needle or through the use of an insulin pen, a specialized insulin injection device that closely resembles an ink pen in appearance. Insulin may also be injected through an insulin pump. Insulin pumps are external devices worn on the body. They connect to an abdominal catheter, through which insulin is administered to the body. Insulin pumps are able to administer extremely precise amounts of insulin at prescheduled times. Some insulin pumps are connected to a blood sugar reader, which allows them to automatically deliver the necessary amount of insulin to a person’s bloodstream. Insulin inhalers are a rapid-acting insulin therapy that a person inhales through the mouth at the start of a meal.

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