Fast-acting insulin formulations are?

• A. Inhaled
• B. SQ, IV
• C. Oral
• D. IM

Answer: (B)

Fast-acting insulin is formulated to start lowering blood glucose quickly to match the rapid rise after a meal. Because insulin is a protein, it would be destroyed by the digestive system if taken orally, so it cannot be effectively delivered that way. The routes that provide fast and predictable absorption are subcutaneous injections and intravenous infusions. Subcutaneous administration covers a meal-time need in everyday diabetes management, while intravenous administration is used in hospital settings when immediate control is required. Although inhaled insulin exists, it is not the standard fast-acting form, and intramuscular use is not preferred due to less consistent absorption.