Illustration of insulin molecules courtesy of Takometer at English Wikipedia
Canine diabetes mellitus is characterized by hyperglycemia caused by an absolute or relative deficiency in the pancreatic β-cell hormone insulin. The production of purified beef and pork insulin is diminishing with the introduction of recombinant techniques for the production of human insulin. The manufacture of recombinant insulin is problematic, as production methods are based on prokaryotic expression systems that lack the intracellular machinery and enzymes required for correct folding and processing of proinsulin to insulin. The gene product, preproinsulin, undergoes substantial post-translational modification in pancreatic β-cells before becoming biologically active. A more efficient method would be to synthesize recombinant insulin that does not require post-translational modification to exert biological activity.