What is the primary method for delivering insulin?

Subcutaneous injection is the primary method for delivering insulin due to the nature of insulin as a peptide hormone. When injected subcutaneously, insulin is absorbed into the bloodstream through the fatty tissue, allowing for a controlled and gradual release into circulation. This method is convenient and effective for self-administration, which is essential for individuals managing diabetes.

In contrast, oral ingestion of insulin is ineffective because the digestive system breaks down insulin before it can enter the bloodstream. Intravenous infusion is generally reserved for hospital settings where rapid insulin action is needed for specific situations, such as severe hyperglycemia or diabetic ketoacidosis. Inhalation is not a standard delivery method for insulin and is typically less common, with limited use in specific formulations designed for inhaled delivery being available only in certain circumstances.