The most commonly recommended needle sizes for insulin pens are 4mm, 5mm, and 6mm.
Recommended Insulin Pen Needle Sizes for Adults
For adult patients, regardless of their Body Mass Index (BMI), healthcare professionals generally recommend using the following needle lengths for insulin pens:
- 4-mm needles
- 5-mm needles
- 6-mm needles
These needle sizes are typically appropriate for subcutaneous injection (injection under the skin, not into the muscle) and help avoid intramuscular injection.
Injection Angle and Longer Needles
- 90-Degree Angle: The board recommends that 4mm, 5mm, and 6mm needles be inserted at a 90-degree angle. This direct injection ensures the insulin is delivered correctly under the skin.
- Longer Needles: If longer needles are necessary, it is important to avoid injecting the insulin into the muscle by utilizing one of two injection techniques:
- Skinfold: Pinch a fold of skin and inject the needle at a 90-degree angle into this fold
- 45-degree Angle: Inject the needle at a 45-degree angle into the skin.
These techniques are important to prevent insulin from being absorbed too quickly, which could lead to hypoglycemia.
Why These Needle Sizes?
The use of 4mm, 5mm, and 6mm needles has been established to effectively deliver insulin to the subcutaneous tissue while minimizing the risk of intramuscular injection and patient discomfort. Shorter needles are usually well tolerated and provide reliable insulin absorption.
