Last Updated on September 10, 2025
Managing insulin properly is essential for safe and effective diabetes care. Insulin is a delicate protein that can lose its effectiveness if stored, handled, or injected incorrectly. Knowing how to store insulin safely, draw insulin into a syringe or pen, and inject insulin correctly helps you keep blood sugar under control and avoid problems like spoiled insulin, air bubbles, or painful injections. This guide walks you through the essentials with simple, practical steps.
Storing Insulin Safely
Why Proper Insulin Storage Matters
Insulin is a protein dissolved in water—think of it like soup stock. It can spoil if it gets too warm or freeze if it gets too cold. Spoiled insulin won’t harm you, but it won’t work as expected, which can lead to higher blood sugar levels even when you take the correct dose.
Refrigeration vs. Room Temperature
- Refrigerate unused insulin between 36º–46ºF (2º–8ºC). If it freezes, it can separate and clump when thawed and is no longer usable.
- In use at room temperature: It’s okay to keep a vial you’re using at 59º–86ºF (15º–30ºC) for up to 28 days. Many people find room-temperature insulin more comfortable to inject, and it may help reduce air bubbles in the syringe.
- Hot climates: If your room temperature stays above ~80ºF (27ºC), keep insulin in the refrigerator when not in use.
- Check dates: Insulin used past 28 days at room temperature or past the box expiration date may still look fine, but can cause control issues and isn’t recommended.
Special Rules for Insulin Pens
- Many insulin pens can be kept at room temperature for up to 2 weeks (check the package insert, your pharmacist, or the manufacturer for your specific pen).
- Store spare (unused) pens in the refrigerator. Do not freeze.
Signs Your Insulin Has Spoiled
- Unexpected high blood sugars despite correct dosing.
- Clumps, strings, or particles (beyond what’s typical for cloudy insulins after mixing).
- Changes in color or clarity for clear insulins.
Free and Discount Insulin Resources
If you can’t afford insulin or don’t have adequate insurance coverage, assistance may be available. Visit helpingpatients.org or call 202-835-3400. Your prescribing clinician can help you apply.
Drawing Insulin Correctly
Mixing Cloudy Insulin Before Use
For NPH, Lente, or Ultralente insulins (cloudy types), roll the vial gently between your hands 10 times before drawing up the dose. These suspensions can settle at the bottom; rolling redistributes particles for an even concentration. Avoid shaking, which creates bubbles that can prevent you from drawing the full dose.
- Prefilled syringes: Roll gently to remix before use.
- Insulin pens with NPH: Roll the pen 10 times, then gently tip it up and down 10 times. Many pens contain a small glass ball to help mix the insulin.
Steps for Drawing Insulin Into a Syringe
- Wash your hands.
- Roll cloudy insulin if needed (see above).
- Clean the vial’s rubber stopper if desired.
- Draw air into the syringe equal to your insulin dose and inject this air into the vial (to prevent a vacuum).
- Invert the vial and syringe, then pull back the plunger to the correct dose.
- Tap out bubbles and re-adjust to the exact dose.
How to Use an Insulin Pen
- Attach a new pen needle and prime per manufacturer instructions.
- Dial your dose—this sets how far the pen’s plunger will advance.
- Insert the needle, press and hold the injection button until the dose counter returns to zero, then keep the needle in place for several seconds before removing.
Insulins That Should Not Be Mixed
- Do not mix Lantus (insulin glargine) in a syringe with any other insulin; mixing alters its action and makes it unpredictable.
- You can take separate injections of Lantus and rapid-acting insulin (e.g., Humalog or Novolog) at the same time, using different syringes and different body sites.
Injecting Insulin the Right Way
Best Injection Sites for Absorption
Insulin is absorbed most consistently from the abdomen. Many people choose to use the abdomen for injections to improve predictability.
Rotating Injection Sites to Prevent Lumps
Repeated injections in the same spot can cause changes in the fat under the skin—either pits (loss of fat) or lumps (lipohypertrophy). Both can alter how insulin is absorbed.
- Inject at least one inch away from your previous site.
- If helpful, imagine a grid on your abdomen (vertical and horizontal lines through the navel, then divide each quadrant again) and rotate through those squares by day.
Correct Injection Angles and Needle Lengths
- Most people can inject at 90º or 45º.
- Thin adults and small children may benefit from a 45º angle or shorter needles to ensure the insulin goes into the fat layer (not muscle).
- Pinch up a fold of skin and fat when needed to avoid intramuscular injections, which can be painful and may act faster than expected.
Do You Need to Clean the Skin First?
If the skin is generally clean and covered by clothing, routine swabbing with alcohol or soap and water is usually unnecessary. Some people even inject through clothing; however, ensure the area is clean and follow your clinician’s advice.
Helpful Insulin Resources
- Aventis (Lantus): www.lantus.com – 866-452-6887
- Eli Lilly (Humalog): www.lillydiabetes.com – 800-545-5977
- Novo Nordisk (Novolog): www.novonordisk-us.com – 800-727-6500
Pumping Insulin provides in-depth information about insulin pumps and day-to-day use. Using Insulin offers step-by-step guidance to improve glucose control, whether you take one injection with pills or multiple daily injections.