Assembly Line

How insulin is made

Most insulin today is brewed by yeast or bacteria carrying a human gene.

stations
7
things upstream
23
raw sources
11
steps from the ground
6

The short version

Engineered E. coli or yeast carrying the human gene grow in stainless steel bioreactors, making a precursor called proinsulin. Bacteria must be broken open and their protein refolded, while yeast secretes it. Centrifuges, filters and several chromatography columns purify the protein, and enzymes convert it to its final form. It is then blended with buffers and filled aseptically in a cleanroom.

  1. Build the strain

    Scientists insert the human gene into E. coli or yeast, then validate the modified cells for productivity, stability and safety before scaling up.

  2. Ferment in steel bioreactors

    The microbe grows in stainless steel vessels while operators hold temperature, pH, dissolved oxygen and nutrient feed in tight ranges, to get as much cell growth and precursor as they can.

    Goes in
    Baker's yeastSugarWaterAir

  3. Harvest the precursor

    E. coli locks the protein in clumps called inclusion bodies and has to be broken open. Yeast secretes it more readily. Centrifuges and filters remove unwanted solids.

  4. Refold and purify

    Bacterial clumps are dissolved and refolded. Precipitation and several chromatography columns then sort molecules by size, charge and how they interact with water. Ultrafiltration concentrates the result.

  5. Cut to the final form

    Enzymes or chemicals trim the precursor into human insulin or one of its rapid- or long-acting analogues, under carefully monitored conditions. A final polishing column cleans it up.

  6. Formulate the solution

    The pure protein is mixed with buffers, preservatives and stabilizers in water for injection. Contamination is the main danger here, so utilities like pure steam have to be flawless.

    Goes in
    Water

  7. Fill aseptically

    Sterile piping carries the solution to lines in a controlled cleanroom that fill vials, cartridges or pens. Each is inspected, labeled and packed.

    Goes in
    Glass bottle
End of the lineInsulin

Worth repeating

  • Frederick Banting and Charles Best first isolated insulin from dog pancreas in 1921.
  • In 1951 Frederick Sanger sequenced insulin, making it the first protein to be fully sequenced.
  • Genentech developed the technique for the first biosynthetic human insulin, Humulin, and Eli Lilly marketed it in 1982.

Back to the ground

Follow every input upstream and insulin starts as these 11 raw sources.

WaterAirSugarcaneSugar beetSilica sandLimestoneRock saltTronaNatural gasCornCrude oil

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Highlighter 6 stations · 16 raw sources Toothpaste 7 stations · 20 raw sources Baker's yeast 6 stations · 3 raw sources Scotch whisky 7 stations · 19 raw sources Mercury 5 stations · 2 raw sources mRNA vaccine 7 stations · 11 raw sources

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Sources

Cite this page: "How insulin is made." Assembly Line, 2026-11-03. https://assemblyline.org/make/insulin

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