Article Sections

Introduction

This article provides an overview of insulin therapy in diabetes mellitus (DM), including indications for insulin use, pharmacology, and administration.

Physiology of insulin

Insulin, a polypeptide hormone synthesized by pancreatic beta cells, is released in response to elevated glucose levels ( Figure 1).  It is formed through a multistep process involving the following ( Figure 2):

  • Insulin mRNA codes for preproinsulin, a larger precursor molecule that begins with a hydrophobic N-terminal signal peptide.
  • The signal sequence guides preproinsulin to the rough endoplasmic reticulum (RER) during translation, where it is cleaved to yield proinsulin.
  • Proinsulin undergoes further protein folding and disulfide bond formation in the RER.
  • Proinsulin is then transported to the Golgi apparatus and packed with endopeptidases into secretory granules.
  • Endopeptidases cleave proinsulin into insulin

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Figures

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Figure 2
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Tables

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