Medicine & USMLE

Insulin Overview

Diabetes Drugs
  1. Insulin Overview
  2. Rapid Acting Insulin
  3. Short Acting Insulin
  4. Intermediate Acting Insulin
  5. Long Acting Insulin
  6. Metformin
  7. Sulfonylureas
  8. Meglitinides
  9. Thiazolidinediones (TZDs)
  10. DPP-4 Inhibitors
  11. Incretin Mimetics
  12. SGLT2 Inhibitors
  13. Alpha Glucosidase Inhibitors
  14. Pramlintide


Insulin is a hormone produced by the pancreas that can also be given as a medication through an injection. Insulin lowers blood glucose, making it important in the treatment of diabetes mellitus. Insulin can also be used to lower potassium levels, so you may also see it used to treat hyperkalemia. Side effects to be aware of include lipohypertrophy and hypoglycemia. Hypoglycemia is most likely to occur at insulin peak times, and if the hypoglycemia becomes severe enough that the patient loses consciousness, glucagon can be given to treat severe hypoglycemia. When administering insulin, be sure to rotate injection sites to avoid lipohypertrophy. Insulin dosages may need to be increased in times of sickness, with use of steroids, and when the body is experiencing stress.

Key Points

  • Insulin Overview
    • Mechanism
      • Lowers blood glucose levels
        • Insulin binds to insulin receptors on the cell, stimulating glucose uptake from the blood into the cell. This lowers glucose levels in the blood.
      • Lowers potassium
        • Insulin increases potassium uptake into cells, reducing blood potassium levels
    • Clinical Uses
      • Treats Diabetes Mellitus
        • Type 1
          • Insulin is the only treatment available for type 1 diabetes.
        • Type 2
          • Insulin is used in type 2 diabetes if the patient doesn’t respond to other forms of treatment, such as diet, exercise, or oral medications.
        • Gestational diabetes
          • High blood sugar that occurs during pregnancy
      • Treats Hyperkalemia
      • Used in Pancreatitis
        • Inflammation of the pancreas can insulin production to drop, requiring the patient to need insulin injections
    • Side Effects
      • Lipohypertrophy
        • Fat buildup at the site of many subcutaneous insulin injections, creating a lump that changes drug absorption and dosing
      • Hypoglycemia
        • Symptoms include shakiness, chills, sweating, tachycardia, irritability, dizziness, hunger, altered level of consciousness, seizures
        • Hypoglycemia is most likely to occur during insulin peak
          • Insulin’s peak refers to when the insulin has the strongest effect. The timing of the peak varies depending on the type of insulin.
          • Closely monitor patients for hypoglycemic reactions around the peak time
        • Glucagon is used to treat hypoglycemia caused by insulin overdose in patients who are unable to tolerate foods/liquids due to decreased level of consciousness
      • Hypokalemia
        • Insulin shifts potassium into the cells, resulting in low potassium in the bloodstream
        • Most likely to occurs after administration of really high doses of insulin (such as after treating diabetic ketoacidosis)
    • Administration
      • Rotate injection sites
        • Each insulin injection should be in a different location than the previous one.
        • This will help prevent lipohypertrophy
      • Increase insulin dosage with stress, sickness, and steroids
        • When the body is under stress (including surgery), sick, or taking steroids, it will require MORE insulin, not less! During these instances the body often has an increase in blood sugar levels so more insulin will be needed.
      • Other administration techniques
        • Refrigerate unopened vials
        • Administer at room temperature
        • Insulin in multi-use vials are good for 30 days from when opened
        • Inject air into multi-use vials before drawing insulin into the syringe
        • Use a special insulin syringe. Insulin dosage is in “units”
        • Give subcutaneously