Pen Needles for Semglee Pen: Which Fit, Best Size, and How Many to Buy

If you've been prescribed Semglee (insulin glargine-yfgn), you'll need to buy pen needles for the Semglee pen separately in most cases. The good news: the Semglee prefilled pen uses the same standard screw-on needle connection as most US insulin pens, so you have plenty of options. This guide covers which pen needles fit, how to pick a length and gauge, and how many to keep on hand.

What Is the Semglee Pen?

Semglee is a long-acting (basal) U-100 insulin glargine. In 2021 the FDA approved it as the first interchangeable biosimilar to Lantus, which means a pharmacist may substitute it for Lantus where state law allows. Many people switch between Lantus SoloStar, Semglee, and unbranded insulin glargine-yfgn because of insurance formulary changes, so it's common to wonder whether your old needles still work.

Short answer: if your previous needles were standard screw-on pen needles, they almost certainly fit the Semglee pen too. Always confirm with the instructions that come with your pen and your pharmacist.

Which Pen Needles Fit the Semglee Pen?

The Semglee pen accepts standard threaded pen needles from the major brands sold in the US, including:

• NovoFine and NovoFine Plus (Novo Nordisk), such as NovoFine Plus 32G 4mm pen needles
• BD Nano 2nd Gen and BD Ultra-Fine (Becton Dickinson), such as BD Ultra-Fine 31G 5mm pen needles
• Other universal screw-on pen needles labeled for use with major insulin pens

Brand matching isn't required: a Novo Nordisk or BD needle can be used on a pen made by a different manufacturer as long as it's a standard screw-on design. If a needle won't thread on straight, stop and try a fresh one rather than forcing it.

Best Pen Needle Size for Semglee: Length and Gauge

Semglee is injected into the fatty layer under the skin (subcutaneous), just like other basal insulins. Widely published injection guidance says shorter needles are enough for most adults:

• 4mm – the most common starting choice for adults and children; usually no skin pinch needed, injected at 90 degrees.
• 5mm – a popular middle ground some people prefer for a more secure feel.
• 6mm and 8mm – still used by some people out of habit or on a provider's advice; longer needles raise the chance of reaching muscle, so a skin lift may be recommended.

For gauge, a higher number means a thinner needle. 32G needles are very thin and many people find them more comfortable; 31G is slightly thicker and can feel steadier with larger basal doses. If you want a deeper comparison, see our guide to pen needles for Lantus SoloStar, since the sizing advice is much the same for any U-100 glargine pen.

Your healthcare provider should make the final call on needle length, injection sites, and your insulin dose.

How Many Semglee Pen Needles Do You Need?

Basal insulin like Semglee is typically injected once a day (sometimes more, depending on your prescription). Because pen needles are single-use, a quick estimate looks like this:

• 1 injection a day: about 30–31 needles per month, so a 100-count box lasts roughly 3 months.
• 2 injections a day: about 60–62 needles per month, or about 7 weeks per 100-count box.
• Also using mealtime insulin or a GLP-1 pen? Add those injections to your monthly total.

Keep a small buffer for priming mistakes or a dropped needle. Most standard screw-on needles also work on other pens you may use, which makes buying one larger box more cost-effective.

Semglee Pen Needle Checklist

• Use a new, sterile needle for every injection, and remove it right after injecting.
• Do a safety test (priming) before each dose as your pen's instructions describe.
• Hold the pen in the skin for the full count listed in your pen's instructions.
• Store unopened needle boxes at room temperature in a dry place, and check the expiration date.
• Dispose of used needles in an FDA-cleared sharps container or a heavy-duty plastic container, following local rules.

FAQ: Pen Needles for Semglee

Do Lantus SoloStar needles fit Semglee?
Standard screw-on pen needles you used with Lantus SoloStar generally fit the Semglee pen as well.

Do I need a prescription for pen needles?
Requirements vary by state and insurance plan. Many people buy pen needles without a prescription, though insurance usually requires one for coverage.

Is 4mm long enough for Semglee?
For most adults, 4mm needles reach the subcutaneous layer, but ask your provider what's right for you.

Shop Pen Needles for Your Semglee Pen

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This article is for general information only and isn't medical advice. Follow your healthcare provider's instructions for your insulin, dose, and injection technique.