Monday’s Google Doodle pays homage to Sir Frederick Banting, a Canadian scientist born 125 years ago, who is best known for co-discovering insulin and first testing it on humans.

His birthday, Nov. 14, also marks World Diabetes Day as his insulin discovery would go on to help millions of people who suffer from the disease.

Diabetes is a result of the body’s inability to naturally produce insulin, a hormone that control the amount of sugar in the blood, or properly use the insulin it produces.

Prior to 1920 there was no treatment for diabetes but previous research had noted that patients with diabetes had a damaged pancreas.

Banting became keenly interested in diabetes after reading a medical article about the pancreas.

In 1921, Banting began to experiment using dogs. He first removed the dog’s pancreas causing it to become diabetic, then he ground up the pancreas and extracted insulin to form an injection. He discovered that giving the dog a few injections a day kept the dog healthy.

Banting and his colleagues realized that they needed more pancreases than the dogs could provide so they quickly moved on to using pancreases from cattle to do more experiments.

Using cow and pig pancreases would remain the mainstay source of insulin until the late 20th century when it was replaced with genetically engineered bacteria.

In 1922, Banting decided to try this injection technique on a 14-year-old boy named Leonard Thompson who became the first person with diabetes to be treated with insulin. The boy responded just as the dogs had.

His work earned him the Nobel Prize in Medicine with his colleague John James Rickard Macleod in 1923. He was also knighted in 1934.

Banting died in February 1941 in an air disaster in Newfoundland during the Second World War while serving as a liaison officer between the British and North American medical services.

His birthday and World Diabetes Day is being celebrated around the world with many people expressing their gratitude for his breakthrough discovery and general contributions to the scientific field.