Longer Is Not Better
Injectable medications such as insulin and glucagon-like peptide-1s (GLP-1s) are most effective when injected just below the skin into fatty tissue so the body can easily absorb and use it. Therefore, a long needle isn’t necessary. In fact, if insulin is injected into muscle tissue it will be used up more quickly than is ideal, which potentially could lead to hypoglycemia. What’s more, if a needle pierces muscle tissue it can cause pain, bruising, and bleeding.
Studies show needle length doesn’t affect blood sugar control. Needles as short as 4 millimeters [mm]) do not appear to impact the function of administered insulin and may actually have advantages over longer needles, since again, they’re can’t reach muscle tissue, making it less likely people who used insulin will skip self-injections to avoid pain.
Some people with diabetes worry that a shorter needle may allow insulin to leak from the injection site, but research has shown this to be an unfounded concern.
Needle Sizes
Insulin pen needles range from 4 mm to 12 mm in length and 29 to 32 gauge in diameter. The lower the number of millimeters, the shorter the needle, while the higher the gauge, the thinner the needle. On average, human skin is 1.6 mm to 2.5 mm thick, so a 4 mm needle will easily breach the skin layer.
4 mm
The smallest, thinnest needle is the nano 4 mm, 32 gauge needle, which is about as thin as two strands of hair. The risk of injecting into muscle tissue is very rare when using this needle, which should not require pinching the skin while injecting (done to pull the fatty tissue away from the muscle for a more accurate injection).
The 4 mm is considered suitable for adults and children. Options in this length include:
GlucoRx 4mm: FinePoint Pen Needles Universal Fit 4 mm 31GBD Micro-Fine Pen Needles 4 mmNovoFine Plus 32G 4 mm
6 mm
The 6 mm mini needle usually comes in a gauge of 31 or 32, making it as thin as the 4 mm option. Options include:
Unifine Pentips 6 mmNovofine Pen Needles 6 mmMyLife Penfine Needles 6 mmGlucoRx FinePoint Pen Needles Universal Fit 6 mm 31G
8 mm
The 8 mm needle is still short and very thin, with an average gauge of 31, but typically requires pinching the skin to get an most accurate dose.
Options in this length include:
GlucoRx FinePoint Pen Needles Universal Fit 8 mm 31GBD Micro-Fine Pen Needles 8 mmMyLife Penfine Needles 8 mmNovofine Pen Needles 8 mmUnifine Pentips 8 mm
10 mm to 12 mm
The 10 to 12 mm length was once the standard needle size, and many people are still accustomed to this length. These needles are very thin, with a gauge size ranging from 29 to 31. There’s a small chance that a longer needle such as the 10 mm or 12 mm size may negatively impact thinner patients who have less subcutaneous fatty tissue to get through before reaching the muscle. Ask your healthcare provider if this length is right for you.
Options in this length include:
Unifine Pentips (10mm)MyLife Penfine Needles (10mm)FinePoint Pen Needles Universal Fit 10 mm 31GFinePoint Pen Needles Universal Fit 12 mm 31GBD Ultra-Fine Pen Needles 12. 7 mm 29G
Reducing Injection Pain
To prevent or lessen pain discomfort while using an insulin pen, regardless of needle size, you can:
Let insulin come to room temperature. Cold insulin can sting—remove it from the fridge 15 minutes before injecting. Allow the alcohol to dry. If you use alcohol to clean and prepare your injection site, allow it to dry before injecting your insulin. Try not to tense up. Before injecting, take deep abdominal breaths and mentally work to relax the muscles at the site where you’ll be injecting. Don’t jabs. Rather, aim for quick, direct penetration. Inject at a 90-degree angle to your skin and do not change the direction of the needle once you are in the injection site. Rotate injection sites. Move the injection site by one inch with each dose to prevent soreness, irritation, or formation of a painful lump. Press, don’t rub. If an injection hurts painful, apply pressure to the site for a few seconds, but do not rub it: This could increase insulin absorption and put you at risk of hypoglycemia.
A Word From Verywell
Always use a new needle for each injection, as repeated use of the same needle increases the risk of infection and may cause the needle to weaken. A weak needle may bend or break during injection or become dull, leading to bruising or bleeding. It’s also important to properly dispose of used needles in a specially marked sharps container for medical waste.
