Insulin [analog] (aka insulin receptor ligand) is an altered form of insulin, differing from any occurring in nature, but still avialable to the human body for performing the same action as human insulin in terms of glycemic control.

• Long/slow acting, to maintain basal insulin, supplying the basal level of insulin required during the day and particularly at night time, that is released slowly over a period between 8-24 hours, including:
  • Detemir insulin (Levemir)
  • Degludec insulin (Tresiba)
  • Glargine insulin (Lantus)
  • Isophane insulin (Protaphane)
• Fast acting, to maintain prandial insulin, through a bolus level of insulin needed at mealtime, which are more readily absorbed from the injection site and thus act faster than natural insulin injected subcutaneously. Correction factor (aka insulin sensitivity) is how much 1 unit of rapid acting insulin will lower BSL's over 2-4 hours when in a fasting or pre-meal state. It includes:
  • Lispro
  • Aspart (NovoRapid)
  • Glulisine

• Insulin can't be taken orally presently, as like all other proteins introduced into the GI tract, it is reduced to fragments (even single amino acid components), where all insulin activity is lost. Routes include:
  • Subcutanoeus injection, by single use syringes with needles, an insulin pump, or by repeated use insulin pens with needles. Patients who wish to reduce repeated skin puncture often use an injection port in conjunction with synringes. Administration schedules often mimic the physiological secretion of insulin by the pancreas, so both long-acting and short-acting insulin are typically used
  • Insulin pump, which has better control over background/basal insulin dosage, with bolus doses calculated to fractions of a unit, and calculators in the pump used to determine the bolus infusion dosages. The limitations are cost, catheter problems, hypoglycemic and hyperglycemic episodes, and no closed looop so controlling insulin delivery is based on current BSL's
• 1 IU (international unit) of insulin is the biological equivalent of 34.7μg pure crystalline insulin. It is derived from the 1 USP insulin unit, which is the amount required to reduce the concentration of blood glucose in a fasting rabbit to 2.5mmol/L

• Through genetic engineering of the underlying DNA, the amino acid sequence of insulin can be changed to alter it's ADME (absorption, distirbution, metabolis, excretion)

• The 1st insulin analog approved for humans was insulin Lispro rDNA, created by Eli Lilly and Company