Complications of Insulin Therapy

Hypoglycemia is the most common and most serious complication of insulin therapy. Hypoglycemia can be potentially life-threatening. Most patients who use insulin experience hypoglycemia at one time or another. If a patient injects too much insulin blood glucose level can fall low enough to cause hypoglycemia.

A number of drugs can potentiate the effects of insulin resulting in hypoglycemia:

  • Alcohol
  • sulfonylurea
  • salicylates
  • phenformin


  • propranolol
  • oxytetracycline
  • ethylenediaminetetraacetic acid (EDT)
  • Mebanazine
  • manganese
  • para-Aminobenzoic acid
  • haloperidol
  • chlorpromazine

Lipoatrophy at injection sites has been associated with all types of insulin, it has an estimated prevalence of 3.6%. The precise pathogenesis remains unclear, but possible mechanisms include immune reaction to insulin or excipients of the injection solution, injury from cold insulin, or trauma from repeated local injections. A study by Lopez, Velazquez, Castells et al. examined subcutaneous biopsies in acute and chronic insulin injection sites. They found atrophy of lobular adipose tissue and variable extent of angiocentric and lobular lymphocytic infiltrate. Focal fibrosis was present in all chronic injection sites.

Chronic use of the same injection site increases the risk of lipoatrophy. Patients learn that these areas become relatively pain free and continue to use them. The fibrotic changes that occur at lipotrophic sites is believed to affect insulin absorption from lipoatrophic areas can result in difficulties in achieving ideal blood glucose control.

Lipohypertrophy is the most common cutaneous complication of insulin therapy. Newer insulins have reduced its prevalence considerably. Lipohypertrophy adverse effects diabetic control by causing erratic release of insulin into the systemic circulation.

Instant Feedback:

Hypoglycemia can occur if a patient injects too much insulin.


The American Diabetes Association's Clinical Diabetes series is an important and rich source of clinical information that every nurse should be familiar with.

For example, visit the Clinical Diabetes web site and search "air travel".

Select the:

Manju Chandran and Steven V. Edelman
Have Insulin, Will Fly: Diabetes Management During Air Travel and Time Zone Adjustment Strategies
Clinical Diabetes April 2003 21:82-85; doi:10.2337/diaclin.21.2.82

Please take note of the effect of distance and direction of air travel on an insulin regimen.