Is insulin still made from pigs? The history and modern production of insulin

October 11, 2025 •

3 min read

While insulin was initially sourced exclusively from animals, including pigs, until the 1980s, the vast majority of insulin used today is not made from animal pancreases. The pharmaceutical industry transitioned to genetically engineered alternatives to meet growing demand and overcome limitations of animal-derived products.

Quick Summary

Modern insulin is produced using genetically engineered bacteria or yeast, replacing the older method of extraction from animal pancreases. This shift to biosynthetic human insulin improved patient safety by reducing allergic reactions and created a reliable, unlimited supply, contrasting with the limited and less pure animal-derived sources.

Key Points

End of Animal Sourcing: Commercial production of insulin from pig pancreases has been discontinued in countries like the US since 2006, replaced by modern methods.
Genetic Engineering Takes Over: Today's insulin is made using recombinant DNA technology, where genetically engineered bacteria or yeast produce insulin that is chemically identical to human insulin.
Improved Purity and Safety: Modern biosynthetic insulin is purer and less likely to cause allergic reactions or immune responses compared to older animal-based versions.
Unlimited and Reliable Supply: Genetic engineering ensures a consistent and scalable supply of insulin that is not dependent on animal agriculture.
Animal Insulin Still Available, But Limited: A few companies still manufacture animal-sourced insulin for specific patients or international markets, but it is not the standard of care.
Addressing Supply and Safety Concerns: The shift to modern production methods resolved issues of supply shortages, allergic reactions, and batch inconsistencies that were prevalent with animal insulin.

From Animal Pancreases to Microbe Factories

Before modern genetic engineering, insulin was extracted from animal pancreases, mainly cattle and pigs, starting in the 1920s. This was the primary method for decades but had drawbacks like dependence on the meatpacking industry and differences from human insulin. Porcine insulin varies by one amino acid, while bovine differs by three. These variations could cause allergic and immune reactions.

By the 1980s, increased demand and concerns about purity and supply led to the adoption of recombinant DNA technology. This allowed microorganisms like bacteria or yeast to produce therapeutic proteins. The first biosynthetic human insulin, Humulin, was FDA-approved in 1982, initiating the move away from animal sources.

How Modern Biosynthetic Human Insulin is Made

Modern insulin production uses genetic engineering for a pure, consistent, and abundant supply chemically identical to human insulin.

The process typically involves:

Creating the Recombinant DNA

Isolating the Human Insulin Gene: The human insulin gene is identified.
Creating Plasmids: A circular DNA piece called a plasmid is taken from a microorganism host, such as E. coli or yeast.
Inserting the Gene: The human insulin gene is inserted into the plasmid using enzymes, creating a recombinant plasmid.

Mass Production and Purification

Bacterial Transformation: Recombinant plasmids are put into host bacteria, which become genetically modified to produce human insulin.
Fermentation: Modified bacteria multiply in tanks, producing human insulin.
Extraction and Purification: Insulin is harvested and purified in multiple steps, removing bacteria and impurities for a highly pure product.

Comparison of Animal vs. Biosynthetic Insulin

This comparison highlights differences between animal-based and modern biosynthetic human insulin.


Feature	Animal-Sourced Insulin (e.g., Porcine)	Biosynthetic Human Insulin
Source	Pancreases of pigs or cattle	Genetically engineered microorganisms (bacteria or yeast)
Chemical Structure	Not chemically identical to human insulin (porcine differs by one amino acid)	Chemically identical to the insulin produced by the human pancreas
Purity	Less pure, can contain trace impurities	High purity
Risk of Allergic Reaction	Higher risk	Significantly lower risk
Supply	Limited, dependent on the meat industry	Virtually unlimited, scalable
Availability	Mostly discontinued in developed countries (US: porcine in 2006)	Widely available and standard of care
Cost	Historically cost-intensive due to extraction process	Production more efficient and scalable, costs remain complex

The Current Status of Animal Insulin

For most patients in developed countries, animal-sourced insulin is no longer the standard. Its voluntary discontinuation in the US, including porcine insulin in 2006, means it's not FDA-approved for domestic sale. However, a small number of patients who respond better may still acquire it under special conditions. Companies like Wockhardt UK continue limited production for specific markets and individual import. Most healthcare providers use modern biosynthetic human insulin and its analogues.

Conclusion

While insulin was once derived from pigs and cattle, this is largely a part of history. The shift to biosynthetic human insulin using genetic engineering has greatly improved diabetes management. It addressed issues of limited supply, inconsistency, and allergic reactions associated with animal-sourced insulin. Today's insulin is purer, more reliable, and safer, offering better treatment options and peace of mind.

Frequently Asked Questions

While major manufacturers in developed countries like the US stopped making insulin from pigs in the 2000s, a few companies in other parts of the world still produce limited quantities for specific markets. Some patients may also be able to import it for personal use under strict regulations.

Modern insulin is produced using recombinant DNA technology. This involves inserting the human insulin gene into the genetic material of microorganisms like E. coli bacteria or yeast. These microbes then act as tiny factories, producing large quantities of human insulin.

The shift from animal-sourced insulin was driven by several factors: the potential for allergic reactions and immune responses due to the subtle chemical differences from human insulin, supply limitations tied to the meat industry, and advancements in more reliable genetic engineering technology.

The key benefits include a reduced risk of allergic reactions because it is chemically identical to human insulin, a virtually unlimited and consistent supply, and greater purity. This provides patients with a safer and more reliable treatment.

Yes, a very small number of patients, typically those who have used animal insulin for decades and respond poorly to modern human insulin, still use animal-sourced products. Access to these insulins is highly restricted and often requires special importation.

Insulin for pets can be different. While some pet owners may use modified human insulin, certain veterinary-approved products, like porcine zinc insulin (Caninsulin) for dogs and cats, are specifically formulated for animal use. It is crucial to use the correct product for each species.

Beyond increased safety and supply, modern production has allowed for the creation of insulin analogues with varied onset times and durations of action (e.g., rapid-acting or long-acting), providing better and more flexible diabetes management for patients.