Which syringe size is primarily used for administering insulin?

The syringe size primarily used for administering insulin is the U-100 syringe. This syringe is specially designed to deliver insulin in units rather than milliliters, which is crucial for accurate dosing of insulin, as insulin concentrations can vary. A U-100 syringe contains markings that reflect the number of insulin units, with 1 mL containing 100 units of insulin. This specificity is essential for managing blood glucose levels in diabetic patients.

Other syringe sizes like 1 mL, 3 mL, and 5 mL are generally used for other types of medications or injections, where precise unit measurement is less critical. Insulin dosing requires careful consideration of the specific units of insulin, making the U-100 syringe the preferred choice for those needs.