The insulin pen is a common device designed to make insulin delivery consistent and convenient. When a dose is due and the pen fails, a missed or partial injection can quickly affect blood glucose control. Prompt and calm action is needed to ensure you receive the correct amount of medication without delay. While mechanical failure can often be resolved, your immediate health needs must be addressed first.
Immediate Safety Checks and Preparation
The first step in any device malfunction is to remain calm and focus on your medical status. High levels of stress can cause a surge in hormones that further elevate blood glucose levels, complicating the situation. You should immediately check your current blood glucose level (BGL) to assess the urgency of the missed dose.
This BGL reading helps determine how quickly you need an alternative delivery method. Before troubleshooting, locate your backup supplies, which should include a spare, functional insulin pen or a vial of the same insulin and syringes. Having a confirmed backup source ready is necessary preparation for a potential complete pen failure. Also, wash your hands to ensure a clean environment for handling the device and insulin.
Step-by-Step Troubleshooting the Device
Troubleshooting a non-working pen often starts with the needle, the most common point of failure. The first action is to remove the current needle and attach a new, unused pen needle securely to the pen’s tip. A needle that is bent, clogged with dried insulin crystals, or incorrectly attached will prevent proper medication flow and plunger depression.
Once a fresh needle is attached, perform a priming or “air shot” test to confirm insulin flow and remove air bubbles. Dial up two units of insulin, hold the pen needle upward, and gently tap the reservoir to encourage air bubbles to rise. Press the injection button fully; a drop or stream of insulin should appear at the needle tip, confirming a clear path. If no insulin appears, repeat the priming step up to three times. If still unsuccessful, the problem is likely with the pen mechanism itself.
Next, examine the dose dial and plunger mechanism, looking for signs of physical damage or resistance. If the dose dial turns freely but the plunger does not advance when the injection button is pressed, there may be a mechanical failure. Temperature extremes can also affect the pen’s mechanism by altering insulin viscosity. Cold insulin is thicker and may cause increased resistance or a jammed plunger. If the pen feels significantly cold, holding it in your hands for a few minutes to warm it slightly may resolve the flow issue.
Alternative Delivery and Next Steps
If troubleshooting confirms the pen is unusable—due to a cracked cartridge, broken dose dial, or repeated failure to prime—switch to an alternative delivery method immediately. The most common and reliable method is using a conventional insulin syringe and a vial of the same insulin. Ensure you use a syringe designed for U-100 insulin, as this concentration is found in nearly all insulin pens, ensuring accurate dose measurement.
You can draw the required dose directly from the cartridge within the failed pen, treating it as a mini-vial, or switch to a new vial and syringe. Since you have already checked your blood glucose, calculate and deliver the full prescribed dose, accounting for any time delay. Never draw insulin into a syringe from a pen and then re-inject the remaining amount back into the cartridge, as this introduces air and compromises future dosing accuracy.
After successfully delivering the dose, contact your pharmacist or healthcare provider immediately to report the pen failure. They can help arrange a replacement pen and review your dose calculation to ensure your safety. The failed pen and its needle should be disposed of safely in a puncture-resistant sharps container. Since the internal components and partially used cartridge are considered medical waste, do not throw the failed pen into the household trash.