Diabetes in Pets

This long abbreviation refers to any insulin made using biotechnology. These are human insulins at present.

r-DNA is the type of process used, GE or GM refer to the resulting type of insulins. Since only human insulin has a large enough market for this expensive effort, all r-DNA insulins are human insulins or analogs (altered insulins). r-DNA processes could in theory be used to make animal insulins as well.

Human insulins you can buy are genetically engineered (GE) insulins or Analog insulins, which are human structure insulins which have various alterations of their amino acids.

Biotech was first used to change pork insulin to human insulin by substituting one amino acid (Alanine at B30 to Threonine)[1][2][3][4]. The result was a Genetically Modified (GM) insulin.

Novo Nordisk produced its human insulins this way from 1981 to 1988[5]. Genetic modification fell out of favor because genetic engineering became less costly.

Biosynthesis, or Genetic Engineering, is currently cheaper than GM. The gene for human insulin (r-DNA) is spliced, or inserted into an organism[6] such as e. Coli (bacteria)[7] or yeast[8] made with a special type of genetically engineered wheat.

Various biotechnical processes then induce the bacteria or yeast to produce human insulin, which is harvested, processed and purified.

Feline insulin compared to Bovine, Porcine and Human versions. Up to 4 amino acids differ. The closest match to feline is bovine with only one amino acid difference; the least close is human with four amino acid differences[9].

Novo Nordisk uses the wheat/yeast process for its insulins[10]; Eli Lilly[11] and Aventis[12] each use e. Coli bacteria and their own patented process to produce their insulins.

Lilly was the first pharmaceutical firm to produce any biosynthetic human insulin. Novo Nordisk was the first to produce human insulin outside of the human body[13]; they initially used the semi-synthetic process described above.

You see here that r-DNA insulin is produced to be a perfect amino acid match to that a human being's body produces naturally. The insulin is one amino acid away from a perfect match to both dog and pig insulin--humans have Threonine at the #30 position on the B insulin chain, while dogs and pigs have Alanine there. For comparing bovine insulin, humans and cows have only the #18 position on the A insulin chain in common, both having Asparagine there. So human and bovine insulins differ by 3 amino acids. Looking at the table for human and cat insulins, there are no matches between the two in any of the 4 key amino acids shown; feline insulin differs from human insulin by 4 amino acids.

Amino Acid Sequence of Insulin Preparations[14]
Amino Acid Substitutions


  A-Chain Position  

B-Chain Position

A-8 A-10 A-21 B-28 B-29 B-30 B-31
Beef Ala Val Asn Pro Lys Ala N/A
Pork Thr Ilc Asn Pro Lys Ala N/A
Human Thr Ilc Asn Pro Lys Thr N/A
Aspart Thr Ilc Asn Aspartic Acid Lys Thr N/A
Lispro Thr Ilc Asn Lys Pro Thr N/A
Glulisine Thr Ilc Asn Pro Glu Thr N/A
Lantus (glargine) Thr Ilc Gly Pro Lys Thr Arg
Levemir(detemir) Thr Ilc Asn Pro Lys N/A Myristic Acid
Ala=Alanine Val=Valine Asn=Asparagine Pro-Proline Lys=Lysine Thr=Threonine Ilc=Isoleucine Glu-Glutamine Gly=Glycine

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