When Was Insulin Invented? A Milestone in Diabetes Care

Insulin was first successfully administered to a person with diabetes in January 1922, following landmark research in Canada. Its discovery changed the outlook for people with diabetes and remains central to care for many people with type 1 and type 2 diabetes today.

When was insulin invented?

Insulin was first successfully used to treat a person with diabetes in 1922. The breakthrough followed experiments in 1921 that showed pancreatic extracts could lower blood glucose in animals. On January 11, 1922, a 14-year-old boy named Leonard Thompson received an early insulin injection in Toronto, Canada. After the preparation was improved, he received a more successful treatment later that month.

It is helpful to think of insulin as a discovery and development process rather than a single moment of invention. Scientists had been investigating the pancreas and diabetes for decades before the Canadian research team isolated a pancreatic extract that could be used clinically. Early insulin was derived from animal pancreases; modern insulin products are carefully manufactured, purified, and tested medicines.

A question about insulin’s history is usually simply educational and is not, by itself, a cause for concern. However, questions often arise because a person has diabetes, has been advised to start insulin, or has noticed symptoms that may relate to blood glucose. In those situations, timely medical advice can provide clear and reassuring guidance.

Why insulin was such an important discovery

Before insulin became available, type 1 diabetes was commonly fatal. Doctors understood that reducing food intake could sometimes temporarily lessen symptoms, but there was no effective way to replace the hormone that the body could no longer make. Insulin made it possible for people with type 1 diabetes to live longer and more active lives when treatment, food intake, and glucose levels were carefully managed.

Insulin is a hormone produced by beta cells in the pancreas. After a person eats, carbohydrates are broken down into glucose, which enters the bloodstream. Insulin helps glucose move from the blood into muscle, fat, and other cells, where it can be used or stored. It also helps the liver regulate the release of glucose between meals.

When too little insulin is available, or when the body does not respond to insulin effectively, glucose can build up in the bloodstream. This is the central problem in diabetes. Understanding insulin’s role also helps explain why diabetes care involves more than one blood test or medication: it may include meal planning, physical activity, monitoring, education, and regular review with a healthcare professional.

Who discovered insulin?

The discovery of insulin is most closely associated with Frederick Banting and Charles Best, who conducted pivotal experiments at the University of Toronto in 1921. John Macleod provided laboratory space, scientific oversight, and support for the work. James Collip then played a key role in purifying the pancreatic extract so that it could be used more safely and effectively in people.

In 1923, the Nobel Prize in Physiology or Medicine was awarded to Banting and Macleod for the discovery of insulin. Banting shared his prize money with Best, while Macleod shared his with Collip, reflecting the important contributions of the broader team. The history is a reminder that major medical advances often depend on collaboration among laboratory researchers, physicians, and patients who take part in early treatment efforts.

Insulin research did not stop in 1922. Over the following decades, scientists improved extraction methods, developed longer-acting preparations, clarified insulin’s chemical structure, and created recombinant human insulin using biotechnology. Today, several insulin types are available, allowing treatment plans to be tailored to an individual’s glucose patterns, daily routine, health needs, and personal preferences.

How insulin treatment has developed

The first insulin preparations were short-acting and were obtained from cows or pigs. Although these treatments were life-saving, they could vary in purity and duration. Researchers later developed intermediate- and longer-acting formulations, which gave people more flexibility and helped cover insulin needs between meals and overnight.

Modern insulin may be described as human insulin or an insulin analogue. Human insulin has the same amino-acid structure as insulin naturally produced in the body. Insulin analogues are modified slightly to change how quickly they begin working or how long they last. Some are designed to work rapidly around meals, while others provide a steadier background effect over many hours.

Delivery options have also expanded. Insulin can be given with syringes, pens, or insulin pumps. Continuous glucose monitors can show glucose trends throughout the day and night for some users. These tools can support decision-making, but they do not replace individual clinical advice. The best option depends on the type of diabetes, other health conditions, access to training, and a person’s ability to use the treatment safely.

Insulin remains essential for people with type 1 diabetes. It may also be prescribed for type 2 diabetes when blood glucose remains above target despite lifestyle measures and other medicines, during pregnancy, around surgery or serious illness, or when the pancreas produces very little insulin. Starting insulin does not mean that a person has failed at diabetes care; it is a medical treatment selected to meet the body’s needs.

Diabetes, insulin, and symptoms to understand

Diabetes is not one single condition. In type 1 diabetes, the immune system damages the insulin-producing beta cells in the pancreas, resulting in very low or absent insulin production. In type 2 diabetes, body tissues become less responsive to insulin and the pancreas may gradually be unable to make enough to compensate. Gestational diabetes develops during pregnancy and also requires careful assessment and management.

High blood glucose may cause increased thirst, frequent urination, tiredness, blurred vision, recurrent infections, slow-healing wounds, or unexplained weight loss. These symptoms can have other causes and do not confirm diabetes on their own. A blood test is needed for diagnosis. Some people with type 2 diabetes have no noticeable symptoms, which is why screening may be recommended based on age, family history, weight, pregnancy history, or other risk factors.

People using insulin should also know the possible signs of low blood glucose, also called hypoglycaemia. Symptoms may include shakiness, sweating, hunger, a fast heartbeat, dizziness, headache, irritability, confusion, or difficulty concentrating. Low glucose can occur if insulin, meals, physical activity, alcohol intake, or illness are not well balanced. A clinician or diabetes educator can explain how to monitor glucose and respond safely according to an individual plan.

Insulin should never be started, stopped, shared, or adjusted without guidance from a qualified healthcare professional. Even when symptoms seem mild, changes in insulin needs can occur with illness, weight changes, pregnancy, kidney disease, new medicines, travel, and changes in eating or activity patterns.

How doctors assess possible diabetes or insulin problems

A doctor will begin by discussing symptoms, medical history, family history, medicines, diet, physical activity, and any history of pregnancy-related diabetes. They may ask whether symptoms developed suddenly or gradually and whether there have been episodes of confusion, fainting, vomiting, or unexpected weight change. This conversation helps identify whether urgent assessment is needed.

Diagnostic testing commonly includes a blood glucose measurement and an HbA1c test, which estimates average blood glucose over roughly the previous two to three months. Depending on the situation, a clinician may use fasting glucose testing, an oral glucose tolerance test, urine testing, or blood ketone testing. These tests help establish whether diabetes is present and whether glucose is currently at a level requiring prompt treatment.

If type 1 diabetes is suspected, doctors may order tests for diabetes-related antibodies and C-peptide, a marker of the body’s own insulin production. Kidney function, cholesterol levels, blood pressure, eye health, and foot health may also be reviewed after a diabetes diagnosis. These assessments help create a long-term care plan and identify complications early, often before a person notices symptoms.

For international patients, Acıbadem Health Point’s multidisciplinary specialists and JCI-accredited hospitals can assess diabetes and develop individualized treatment plans, including education on insulin use and glucose monitoring.

When to seek medical care

Anyone with persistent thirst, frequent urination, unexplained weight loss, new blurred vision, ongoing fatigue, or repeated infections should arrange a medical review. These concerns are often treatable, and prompt testing can clarify whether diabetes or another condition is contributing. People who have risk factors for type 2 diabetes should ask a clinician whether routine screening is appropriate.

Urgent medical assessment is important if a person has symptoms of very high glucose along with vomiting, stomach pain, deep or rapid breathing, severe weakness, confusion, or unusual drowsiness. These symptoms can indicate a serious diabetes-related emergency, particularly in someone with type 1 diabetes or newly developing diabetes. Emergency care is also needed for loss of consciousness, a seizure, or severe confusion that may be related to low blood glucose.

People prescribed insulin should contact their diabetes team if they are having repeated low glucose episodes, persistently high readings, problems with injections or pump equipment, or difficulty managing insulin during illness. Keeping a record of glucose readings, meals, activity, symptoms, and medicines can help the clinician identify patterns and make safer adjustments.

Frequently asked questions