Insulin for Diabetes Treatment (Types, Side Effects, and Preparations)

Medically Reviewed on 11/7/2022

What are the symptoms of diabetes?

Symptoms of diabetes include:


Diabetes: What Raises and Lowers Your Blood Sugar Level? See Slideshow

What are examples of insulin preparations available?

Insulin preparations

  • Examples of rapid acting insulin
    • Apidra (insulin glulisine): Supplied in a cartridge, vial, prefilled pen (Solostar)
    • Novolog (insulin aspart): Supplied in a cartridge, vial, prefilled pen (FlexPen)
    • Humalog: (insulin lispro): Supplied in a cartridge, vial, prefilled pen (Kwik Pen)
  • Examples of short acting insulin
    • Novolin R, Humulin R (regular insulin): Supplied in a vial
    • Velosulin (insulin with a phosphate buffer): Supplied in a pump device
  • Examples of intermediate acting insulin
    • Humulin N, Novolin N (NPH): Supplied in a vial, pen (Humulin N pen)
  • Examples of long acting insulin
    • Lantus (insulin glargine): Supplied in a vial, cartridge (OptiClick), prefilled pen (Solostar)
    • Levemir (insulin detemir): Supplied in a vial, prefilled pen (FlexPen)
    • Tresiba (deglutec injection): Supplied in a vial 

For what type of diabetes is insulin prescribed?

Indications for insulin

What are the side effects of insulin?

Common and Serious Side Effects of Regular Insulin
Common Side Effects Frequency Serious Frequency
Hypoglycemia >40% Severe hypoglycemia n/a
Headache 12% to 35% Allergic reactions n/a
Flu-like symptoms 13% Anaphylaxis n/a
Weight gain 33% Hypokalemia n/a
Lipoatrophy n/a
Itching n/a
Rash n/a
Injection site reaction n/a
* n/a = not available

What is the dosage and how is insulin administrated?

Dosage and Administration of insulin

  • A meal should be consumed within 30 minutes after administering regular insulin
  • Insulin usually is administered by subcutaneous injection into the abdominal wall, thigh, buttocks (gluteal region), or upper arm. Injection sites should be rotated within the same region.
  • Some insulins (for example, regular insulin) also may be administered intravenously.
  • The dose is individualized for each patient.
  • A combination of short or rapid-acting and intermediate or long-acting insulin typically are used
  • Some patients may develop insulin resistance and require increasing doses.
  • Multiple daily insulin injections or continuous subcutaneous infusions via a pump closely mimic pancreatic insulin secretion.
  • Insulin sliding scales (doses of insulin that are based on the glucose level ) may be used for managing critically ill hospitalized patients.

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What are the contraindications, warnings, and precautions for insulin?


Warnings and Precautions

  • Hypoglycemia may occur and is the most common side effect of insulin treatment.
  • Severe, life-threatening allergic reactions, including anaphylaxis, may occur.
  • Hypokalemia (low blood potassium) may occur because insulin stimulates the movement of potassium from the blood into cells. Combining insulin with potassium-lowering drugs may increase the risk of hypokalemia.
  • Hepatic (liver) impairment may reduce insulin requirement.
  • Renal (kidney) dysfunction may reduce the insulin requirement.
  • Illness, emotional disturbance, or other stress may alter the insulin requirement.
  • Intravenous administration increases the risk of hypoglycemia and hypokalemia.

Which drugs interact with insulin?

Insulin Drug Interactions

Examples of Regular Insulin Drug Interactions
Drug or Drug Class Effect Recommendation
Beta-blockers (for example, propranolol [Inderal, Inderal LA, Innopran XL], atenolol [Tenormin]) Beta-blockers may mask symptoms of hypoglycemia or prolong hypoglycemia and alter glucose metabolism Avoid combination if possible
repaglinide (Prandin) Increased risk of hypoglycemia and heart attack (myocardial infarction) Avoid combination if possible
rosiglitazone (Avandia) or rosiglitazone combination products Increased incidence of hypoglycemia, fluid retention, ischemia (manifest by angina or heart pain), congestive heart failure Avoid combination if possible
Thiazides and thiazide combination products Hyperglycemia; may reduce the effect of insulin Monitor glucose levels and adjust accordingly
Corticosteroids Hyperglycemia; may reduce the effect of insulin Monitor glucose levels and adjust accordingly
Estrogens Hyperglycemia; may reduce the effect of insulin Monitor therapy and adjust as needed
levofloxacin (Levaquin) and other fluoroquinolones Increased risk of hypoglycemia or hyperglycemia Use with caution, monitor therapy
Monoamine oxidase inhibitors (MAOIs) MAIOs may increase insulin secretion. The combination increases the risk of prolonged hypoglycemia. Monitor glucose levels and adjust accordingly
Sulfonylureas Increased risk of hypoglycemia and Monitor glucose levels and adjust accordingly
Thyroid hormones Thyroid hormones may increase insulin requirement Monitor glucose levels and adjust accordingly
Yohimbe Yohimbe may increase the risk of hypoglycemia Caution is advised

How well does insulin treat diabetes?

Efficacy of insulin

  • In a 24-week study of patients with type 1 diabetes, regular human subcutaneous insulin (mean dose = 18.3 IU) before breakfast and dinner plus human insulin isophane suspension twice daily (mean dose = 37.1 IU) reduced HbA1c by 0.4% from baseline and fasting glucose by -6 mg/dl.
  • In a 24-week study of patients with type 2 diabetes, regular human subcutaneous insulin (mean dose = 25.5 IU) before breakfast and dinner plus human insulin isophane suspension twice daily (mean dose = 52.3 IU) reduced HbA1c by 0.6% from baseline and fasting glucose by -6 mg/dl.

What is the mechanism of action (how it works) for insulin?

Pharmacology (mechanism of action) of insulin

Insulin is a hormone secreted by the pancreas. It regulates the movement of glucose from the blood into cells. Insulin lowers blood glucose by stimulating peripheral glucose uptake primarily by skeletal muscle cells and fat, and by inhibiting glucose production and release by the liver. Insulin inhibits lipolysis (breakdown of fat), proteolysis (breakdown of proteins), and gluconeogenesis (manufacture of glucose). It also increases protein synthesis and the conversion of excess glucose into fat. Insulins used to treat diabetes are pharmacologically similar to the naturally produced hormone. Patients with diabetes are insensitive to insulin and do not produce enough insulin which leads to hyperglycemia and symptoms of diabetes. Exogenous insulin preparations replace insulin in diabetics, increasing the uptake of glucose by cells and reducing the short and long-term consequences of diabetes.


There are a variety of types and preparations of insulin for the treatment of type 1 and type 2 diabetes, gestational diabetes, diabetes during pregnancy, metabolic syndrome, and insulin resistance. Human insulin preparations and regular insulin are made by recombinant DNA technology. Examples of preparations of insulin include rapid acting insulin (Apirda, Novolog, Humalog), short acting insulin (Novolin R, Humulin R), intermediate acting insulin (Humulin N, Novolin N, and long lasting insulin (Lantus, Levemir). Common side effects of insulin include hypoglycemia, headache, weight gain, rash, itching, flu-like symptoms, lipoatrophy, and reaction at the site of injection. Warnings, precautions, and drug interactions should be reviewed prior to taking insulin.

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Medically Reviewed on 11/7/2022
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