How Do Insulins Work?

Insulins are a class of drugs used to treat type 1 (T1DM) and type 2 diabetes mellitus (T2DM). T1DM is a condition caused by an autoimmune reaction that destroys the beta cells of the pancreas because of which the body cannot produce or synthesize insulin needed to manage circulating blood sugar levels and therefore the amount of sugar in the blood cannot be controlled. T2DM is a slowly progressive metabolic disorder caused by a combination of genetic and lifestyle factors that promote chronically elevated blood sugar levels.

Insulin is a peptide hormone produced by the beta cells of the pancreas to help metabolize food and use it for energy throughout the body. After a meal, insulin promotes the uptake of glucose (a type of sugar found in many carbohydrates) from the blood into internal organs and tissues such as the liver, fat cells, and skeletal muscles. It allows the body to use glucose for energy; helps in the storage of glucose in the liver, fat, and muscles; and regulates the body’s metabolism of carbohydrates, fats, and proteins.

In nondiabetic conditions, insulin helps in:

• Regulating blood sugar levels: after meals, carbohydrates are broken down into glucose (the body’s primary source of energy) which then enters into the bloodstream. In addition, the pancreas produces insulin, allowing glucose to enter the body's cells to provide energy.
• Storing excess glucose for energy: after eating when insulin levels are high, excess glucose is stored in the liver in the form of glycogen.

The general types of insulin therapy include:

• Long-acting insulin: in between meals, the liver releases glucose so that there is a continuous supply of energy in the body; this insulin helps the body use the glucose and prevent it from reaching excessively high levels.
• Intermediate-acting insulin: takes two to four hours to work fully and their effects can last up to 18 hours.
• Rapid- or short-acting insulin: ideal for preventing blood sugar spikes after meals. They begin to work much faster than long- or intermediate-acting insulins but for a shorter period of time, usually about two to four hours.

Without an adequate supply of insulin to promote absorption of glucose from the bloodstream, blood sugar levels can rise to dangerously high levels and can result in symptoms such as fatigue, headache, blurred vision, and increased thirst. If left untreated, the body starts to break down fat instead of glucose for energy, resulting in the build-up of ketone acids in the blood and a syndrome called ketoacidosis, which is a life-threatening medical emergency. In the long term, elevated blood sugar levels increase the risk of heart attack, stroke (loss of blood flow to part of the brain), and diabetic neuropathy.

Insulins are administered as a solution (liquid) and suspension (liquid with particles that will settle on standing) to be injected subcutaneously (under the skin), a powder to be orally inhaled using a special inhaler, an injectable pen, and prefilled pens.

Insulins work in the following ways:

• They are man-made products similar to human insulin which replace the insulin made by the body. 
• They help in the blood sugar (glucose) movement into the cells so that the body can use it for energy.
• In addition, they prevent the liver from producing more sugar (inhibits hepatic glucose production).

Insulins are indicated to improve glycemic control in patients with T1DM and T2DM along with a proper diet and exercise.

Some of the common side effects include:

• Injection site reaction (pain, redness, and irritation)
• Weakness
• Constipation
• Tiredness
• Sore throat or irritation
• Nausea
• Headache
• Dyspepsia (a feeling of burning, pain, or discomfort in the digestive tract)
• Diarrhea

Other rare side effects include:

• Weight gain
• Hypokalemia (low blood potassium level)
• Muscle cramps
• Irregular heartbeats
• Dizziness (feeling faint, weak, or unsteady)
• Swelling of the arms, hands, feet, ankles, or lower legs
• Shortness of breath
• Pharyngitis (inflammation of the pharynx, which is in the back of the throat)
• Rhinitis (inflammation and swelling of the mucous membrane of the nose)
• Local allergic reaction
• Tremors (a rhythmic involuntary shaking movement in one or more parts of the body)
• Mental confusion
• Lipodystrophy (a problem with the way the body uses and stores fat)
• Hypoglycemia (low blood sugar level)
  • Sudden sweating
  • Fast heartbeat
  • Blurred vision
  • Tingling in hands/feet

Information contained herein is not intended to cover all possible side effects, precautions, warnings, drug interactions, allergic reactions, or adverse effects. Check with your doctor or pharmacist to make sure these drugs do not cause any harm when you take them along with other medicines. Never stop taking your medication and never change your dose or frequency without consulting your doctor.

Generic and brand names of insulins include:

• Admelog
• Admelog Solostar
• Afrezza
• Apidra
• Apidra Solostar
• Basaglar
• Fiasp
• Humalog
• Humalog Junior KwikPen
• Humalog Kwikpen
• Humalog Mix 50/50
• Humalog Mix 50/50 Kwikpen
• Humalog Mix 75/25
• Humalog Mix 75/25 Kwikpen
• Humulin 70/30
• Humulin N
• Humulin R
• Humulin R U-500
• Insulin aspart
• Insulin aspart protamine/insulin aspart
• Insulin degludec
• Insulin detemir
• Insulin glargine
• Insulin glulisine
• Insulin inhaled
• Insulin isophane human/insulin regular human
• Insulin lispro
• Insulin lispro protamine/insulin lispro
• Insulin lispro-aabc
• Insulin NPH
• Insulin regular human
• Lantus
• Lantus SoloStar
• Levemir
• Levemir FlexTouch
• Liraglutide/insulin degludec
• Lyumjev
• Myxredlin
• Novolin 70/30
• Novolin N
• Novolin R
• NovoLog
• NovoLog FlexPen
• NovoLog FlexTouch
• NovoLog Mix 50/50
• NovoLog Mix 70/30
• NovoLog Mix 70/30 FlexPen
• NovoPen Echo
• Semglee
• Toujeo
• Tresiba
• Xultophy