An insulin needle is commonly used with a syringe to inject insulin into the body. The needle is very thin and designed for one-time use. Needles should always be injected directly into the skin (not through clothing) at a 90-degree angle to minimize insulin leakage.
Needles are measured by their length and gauge, or thickness. The previously common recommendation to use a 12-millimeter or even 16-millimeter needle is now considered outdated based on more current research. Doctors now recommend using a 4-millimeter, 6-millimeter, or 8-millimeter needle. Modern needles of 4 or 6 millimeters are short enough to not require pinching the skin before injection.