Needle length

Learn how shorter needles can help improve your diabetes management

You may not realize it, but the length of your pen or insulin syringe needle plays an important part in your diabetes management. Your needle is responsible for making sure your medication goes where it needs to, and it can even help you reach more injection sites.1,2

The proper depth for injection.

To work properly, insulin and GLP-1 need to be injected into the subcutaneous (SC) tissue layer, which is the fatty layer just under your skin. This way, your body can absorb them predictably.1

An injection that goes deeper than the SC tissue and into your muscle is called an intramuscular (IM) injection. An IM injection can cause your body to absorb insulin unpredictably, which may lead to poor glycemic (i.e., blood sugar) control and hypoglycemia (i.e., "hypo" or low blood sugar).1

So how can you avoid IM injections? The average skin thickness across the four most common injection sites—the abdomen, thighs, buttocks and arms—is just 2.0 to 2.5 mm.2 This means you do not need a needle much longer than that to reliably and safely inject your insulin or GLP-1 into the SC tissue layer.

In fact, scientific studies have shown that a 4-mm pen needle is estimated to deliver insulin to the SC tissue layer more than 99.5% of the time.2

Easier injections for all types of people

Another advantage to using a 4-mm pen needle is that it eliminates the need to apply a skin lift technique to inject.2* Instead, you can inject at 90 degrees with only one hand, enabling you to more easily reach more injection areas—including the back of your arms.2

If you use an insulin syringe with a 6-mm needle and are slim (or lean), you may need to inject at 90 degrees while applying a skin lift technique.3

When you rotate properly to more injection sites, you reduce your risk of complications like lipohypertrophy. This approach can help keep your blood sugar on track.

The latest recommendations from diabetes experts for best practices in injection technique (FIT Canada) say that current research across a wide range of BMIs (19-65 kg/m2) supports the use of 4-mm pen needles to avoid the risk of intramuscular injection.3

Injection technique is critical to good diabetes management.

Learn more

Learn how to inject using a pen or insulin syringe needle


*Children from 2 to 6 years old or extremely lean adults may need to use a skin lift technique.3

  1. Frid AH, Kreugel G, Grassi G, et al. New insulin delivery recommendations. Mayo Clin Proc. 2016;91(9):1231-1255.
  2. Gibney MA, Arce CH, Byron KJ, Hirsch LJ. Skin and subcutaneous adipose layer thickness in adults with diabetes at sites used for insulin injections: implications for needle length recommendations. Curr Med Res Opin. 2010;26(6):1519-1530.
  3. Berard L, Desrochers F, Hagerty D, MacNeill G, Roscoe R. FIT Forum for Injection Technique Canada: Recommendations for best practice in injection technique (3rd edition). Accessed May 30, 2017.