On May 17, 1921, Frederick Banting and Charles Best began their summer project at the University of Toronto in the Connaught Antitoxin Laboratory, which was run by John James Rickard Macleod. Less than a year later, Leonard Thompson, a 14-year-old boy suffering from Type 1 diabetes, became the first patient to be successfully treated with insulin injection. 

The discovery of insulin by Banting and Best was a watershed moment in the history of diabetes since the condition was essentially a death sentence for children before 1922. Today, people with diabetes can manage their blood sugar and lead fulfilling lives because of insulin. 

It is undeniable that Banting and Best have altered the lives of many people with diabetes since 1921. As U of T celebrates the 100 year anniversary of their achievement, reviewing the timeline of events shows how Banting and Best owed their discovery of insulin to many researchers who came before them. 

How it all began 

The history of the discovery of insulin began in 1869 when Paul Langerhans, a medical student in Germany, identified the so-called ‘islets of Langerhans’ in the pancreas groups of cells responsible for insulin production. 

At the end of the 1800s, French scientist Eugène Gley demonstrated that a pancreatic extract was able to reduce blood glucose levels in dogs without a pancreas. This was followed by the work of Eugene Lindsay Opie in 1901, which showed that destruction of the islets of Langerhans caused diabetes. 

Armed with this new knowledge, scientists spent the next two decades trying to isolate the mysterious compound from the pancreas with little success. While they knew that the islets of Langerhans were the sources of the anti-diabetic extract, scientists at the time faced the challenge of separating these islets from the rest of the pancreas. 

This was when Banting entered the picture. 

Inspired by an article he read on pancreatic duct binding, Banting came up with his own experiments and approached Macleod in 1920 with his plan. Macleod agreed to lend him his lab space at U of T and a student assistant, 22-year-old Charles Best. 

Banting designed a new technique to occlude the pancreatic duct, which enabled further procedures to be carried out without destroying the islets. Banting and Best found that in dogs without a pancreas, the preservation of the islets was sufficient to prevent the development of diabetes. 

By July of 1921, the two had successfully isolated the elusive anti-diabetic extract that had evaded others for so long — insulin. With the help of the biochemist James Bertram Collip, they were able to produce a safe and stable version of insulin for use in humans. On January 11, 1922, 14-year-old Thompson received an injection that would allow him to live for another 13 years.

Distribution in Canada and beyond 

Nothing illustrates the importance and urgency of insulin than the speed of its distribution. 

Although the Connaught lab was producing insulin for all Canadians in 1922, it did not have the capacity for global demand. To manufacture the newly discovered insulin on a large scale, the governors of U of T came to an agreement with the pharmaceutical company Eli Lilly & Co of Indianapolis in the spring of 1922. Macleod also started to share his recipe for insulin with other physicians in the US, who used it for clinical and experimental purposes. 

In October 1922, Danish Professor August Krogh and his wife, Mary Krogh, a physician who took care of patients with diabetes, brought insulin to Denmark. In November of the same year, Canada gifted the patent of insulin to Great Britain and Ireland. By May 16, 1923, Britain became the first country to make insulin commercially available.

Then, the agreement between U of T and Eli Lilly came to an end in June 1923, allowing for other manufacturers to acquire the right for insulin production. Insulin was finally made commercially available in the US and Canada on October 15, 1923. By 1924, insulin was distributed in countries all over the world.

Diabetes in the modern day

A century after its discovery, insulin continues to be an integral part of the lives of people with diabetes. For them, management of their blood glucose is critical since uncontrolled diabetes can lead to serious complications such as kidney failure, blindness, and nerve damage. 

Since insulin’s discovery a century ago, scientists have been improving its pharmacological profile to mimic its natural secretion. We now have short- and long-acting insulin and even insulin pumps that can be programmed to release insulin according to the wearer’s mealtimes.

However, despite these advancements, complete insulin replacement remains elusive.

To control their blood glucose level, people with diabetes approximate natural insulin secretion with stringent glucose monitoring and insulin injection as appropriate. They must also adjust other behaviours such as dietary choices and physical activities.

This regimented lifestyle can be exhausting. Marley Greenberg, a fourth-year student and the president of the College Diabetes Network at U of T, has been living with Type 1 diabetes since she was eight years old. For her, diabetes is a full-time job. 

“I’m constantly checking my blood sugars, giving insulin on my pump, and counting every carbohydrate I eat,” she wrote in an email to The Varsity. “Stress and hormones can make my blood sugars go high, and there’s really no way of knowing how much insulin I’ll need to balance out things like exam-season stress.” 

“Something as simple as walking from one class to another can make my blood sugars go low. There’s so many factors to consider, and there’s never a break from management. The psychological weight of diabetes can be heavy and many people experience burn-out.”  

Greenberg also emphasized the importance of peer support, especially for young people with diabetes.

“Type 1 diabetes often feels like an invisible illness, and it can be misunderstood and isolating. I’ve found that connecting with other young adults with diabetes is one of the best sources of support,” she wrote. “That’s why we run the College Diabetes Network chapter at U of T, to help students feel less alone. Sharing the mental weight of diabetes with people who get it can make this condition feel a lot lighter.” 

The cost of insulin

Banting, Best, and Collip sold the patent for insulin to U of T for $1 following the success story of Thompson.

“Insulin does not belong to me; it belongs to the world,” said Banting at the time.

Yet, contrary to Banting’s vision, insulin does not belong to everyone today. In fact, many of the 11.5 million Canadians living with diabetes cannot afford insulin despite it being a life-saving treatment.

Since Canada does not have a nationwide pharma care plan to cover insulin costs, many Canadians pay out of pocket to obtain insulin. In Ontario, adults aged 25 or older who lack private insurance must pay out of pocket for insulin, and many people still struggle to afford this life-saving drug.

According to Diabetes Canada, people with diabetes can be expected to pay anywhere from $1,100–$4,900 per year depending on the types of insulin that they use. This does not include the cost of other diabetes supplies such as blood glucose strips and glucose monitoring devices.

Those who cannot afford the costs have to choose between insulin and paying for their food or rent. Last year, professor and physician IIana Halperin tweeted about a 26-year-old graduate student at U of T who was having difficulty paying for her insulin. The student was no longer qualified for Ontario’s drug coverage plan and had depleted her university insurance.

Halperin wrote that the student was rationing insulin by taking just enough of the drug to prevent her from going to the hospital, but not enough to sufficiently manage her blood glucose levels.

Greenberg and her family also experience the financial strain of insulin treatment. Greenberg’s mother, Dana Greenberg, who also lives with Type 1 diabetes, described the immense costs of paying for both of their diabetes supplies over the years in an email to The Varsity. “Having no private health insurance, the financial burden of keeping Marley and me not just alive but healthy is enormous. In 2021, people with diabetes shouldn’t still be struggling to afford insulin.”

Policies around diabetes need to catch up with scientific innovations. Unless we solve the issue of accessibility, there will be no real progress for people living with diabetes.

The story of insulin began over 100 years ago, but it is nowhere near finished. Today, millions of people around the world are writing the next chapter.