Insulin is a hormone that plays a central role in regulating blood sugar levels in the body. It enables cells to absorb glucose from the bloodstream, converting it into energy or storing it for later use. For individuals living with diabetes, the body either does not produce enough insulin or cannot effectively use the insulin it produces, leading to elevated blood sugar. Historically, obtaining this hormone for medical treatment presented a significant challenge.
Historical Discovery and Early Sources
The discovery of insulin occurred in the early 1920s at the University of Toronto. Researchers Frederick Banting, Charles Best, John Macleod, and James Collip identified the pancreas as the source of a substance capable of lowering blood sugar. Their initial experiments extracted this substance from the pancreases of dogs. This extract, later named insulin, improved the health of diabetic dogs.
Following these successful animal trials, the team refined the extraction process for human use. The first human patient, Leonard Thompson, received an insulin injection in January 1922, showing improvement. This led to the large-scale production of insulin, primarily sourced from the pancreases of animals such as pigs and cattle. These animals were chosen because their pancreases were available from the meatpacking industry, and due to their insulin’s physiological similarity to human insulin.
Porcine Insulin’s Role and Characteristics
Porcine insulin, derived from pigs, played a significant role in diabetes management for decades. Its widespread use stemmed from its close structural resemblance to human insulin. This meant that porcine insulin was largely effective and well-tolerated by most patients.
Obtaining porcine insulin involved collecting pancreases from slaughtered pigs, grinding them into a slurry, and then chemically extracting and purifying. This method enabled mass production of insulin, transforming diabetes from a rapidly fatal condition into a manageable chronic disease. For many years, porcine insulin was the standard treatment for regulating blood sugar levels in individuals with type 1 and advanced type 2 diabetes.
Modern Insulin Production
The landscape of insulin production shifted significantly with the advent of modern biotechnology, particularly recombinant DNA technology. In the early 1980s, scientists developed methods to produce human insulin synthetically, primarily using bacteria like Escherichia coli or yeast. This process involves inserting the human insulin gene into the genetic material of these microorganisms, which then act as “biological factories” to produce insulin identical to that found in humans.
This technological advancement offered several advantages over animal-sourced insulin. Recombinant human insulin provides a more consistent and virtually unlimited supply, increased purity, and a reduced risk of allergic reactions or immune responses sometimes associated with animal-derived proteins. While animal insulin was revolutionary in its time, it has largely been replaced by these advanced methods in contemporary medical practice. Porcine insulin was discontinued in the U.S. in 2006, though it may still be available in some other parts of the world.