Treating Diabetes: 1921 to the Present Day

Before the discovery of insulin, a diagnosis of diabetes meant certain death.

The lives of people with diabetes has changed considerably in 50 years. They now have specific tools and easier access to information than ever before. The healthcare professionals who treat them also know more about the complexity of the disease, and which treatments work best.

Pending the next medical revolution, Diabetes Québec is demanding the implementation of a national strategy to fight diabetes – a strategy founded on education, prevention, support and treatment. The last 60 years have clearly demonstrated that people with diabetes who are well informed, properly supported and treated appropriately live longer lives in better health.

The discovery of insulin and glycemic control

Insulin, discovered in 1921 by the legendary Banting, Best and MacLeod collaboration, is nothing short of a miracle. Worldwide, it has saved thousands of patients from certain death.

Before the discovery of insulin, diabetics were doomed. Even on a strict diet, they could last no more than three or four years.

However, despite the many types of insulin and the first oral hypoglycemic agents that came to market around 1957 in Canada, glycemia control – the control of blood glucose (sugar) levels – still remains an imprecise science.

In the 1950s, the method a person used to control his blood glucose levels was to drop a reagent tablet into a small test tube containing a few drops of urine mixed with water. The resulting colour – from dark blue to orange – indicated the amount of sugar in the urine.

Even when they monitored their patients closely, doctors realized that blood glucose levels had to be much better controlled in order to delay the major complications significantly affecting their patients’ lives: blindness, kidney disease, gangrene, heart attack and stroke.

A discovery

Belgian doctor Jean Pirart, a pioneer in diabetes treatment, discovered the link between good glucose control and the prevention of complications.

Between 1947 and 1973, Dr. Pirart divided more than 4,000 patients into three groups based on their level of blood sugar control: good, fair, poor. Using reagent tablets as the measurement method, Dr. Pirart’s findings clearly demonstrated a higher incidence and prevalence of complications in patients with poor glycemic control.


The 1970s and 1980s marked are a turning point in the treatment of diabetes. Innovations such as blood glucose readers and strips measuring blood glucose (sugar) levels gave people with diabetes and their doctors some indispensable tools.

In 1976, American scientists discovered that sugar attaches to red blood cells (hemoglobin) and that this could be used to determine how well blood glucose had been controlled in the previous two to four months. This discovery led to the creation of the glycated hemoglobin (A1C) test.

The advent of monitoring tools enabled researchers to create large-scale studies. Their findings changed the way diabetes was treated.

Then two important studies, the Diabetes Control and Complications Trial (from 1983 to 1993) and the United Kingdom Prospective Diabetes Study (from 1977 to 1997), showed, for both types of diabetes, that maintaining blood glucose (sugar) levels close to normal values delays and slows the onset of chronic complications from diabetes.

The arrival of insulin therapy

Intensive insulin therapy – multiple injections of insulin mimicking the normal functioning of the pancreas – appeared in the treatment of type 1 diabetes, and now is an increasingly popular treatment option for type 2 diabetes.

The story of the first insulin injection

On December 2, 1921, Leonard Thomson, 14, arrived at the emergency of Toronto General Hospital. He weighed just 65 pounds (30 kg) and his life hung by a thread. His diabetes had been diagnosed two years earlier.

In hospital, although Thomson was put on a strict diet of 450 calories a day, his blood glucose easily reached 28 mmol / L, and he was always in a state of acidosis. The doctors gave him only weeks to live.

On the track of insulin

For several months, two researchers, Dr. Frederick Banting and Charles Best, under the direction of Dr. John Macleod, had been searching for the mysterious substance that plays the key role in diabetes. They had succeeded in isolating a substance from a dog pancreas and injecting it into other dogs whose pancreas had been removed. They had learned that these diabetic dogs could be saved by this substance.

However, the results were highly variable because the researchers had not been able to sufficiently purify the insulin and had been injecting a mixture of insulin and other substances.

A question of purity

A young chemist by the name of James Collip subsequently joined the group. His goal: to obtain pure insulin. Without him, the team would never have obtained positive results as quickly. While Banting and Best continued their research on dogs, Collip used beef pancreases to refine his insulin-extraction technique and, very quickly, decided to use different concentrations of alcohol.

The first injection

On January 11, 1922, the first injection was given to young Leonard Thomson. Tests were done the next day: his blood glucose had fallen from 24.5 to 17.8 mmol / L., but there was still a lot of sugar in his urine. The first injection was a partial failure because the injected insulin was not pure enough.

The second injection

Twelve days after the first injection, after repeatedly testing his insulin, Collip felt ready to repeat the injections on Thomson. This time, they were a success. Thomson’s blood glucose dropped from 28.9 to 6.7 mmol / L., and there was practically no sugar in his urine. For the next two days, Thomson did not get an injection and his blood glucose rose. In the weeks that followed, he got daily injections. He gained weight and strength. Researchers knew that they had made a great discovery.

By February 1922, six other diabetics had been given the extract with the same positive results. They called the extract isletin. It was not until April 1922 that it was given its final name: insulin.

Niny six years later, millions of people are alive thanks to one of the greatest discoveries of the 20th century.


Research and text: Diabetes Québec Team of Health Care Professionals

November 2016 (updated on July 2018)

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