Test Strips and Lancets: Storage, Use, and When to Replace Them
✓ Medically reviewed by a licensed Canadian pharmacist · Updated July 4, 2026
Your readings have gone strange, or every finger prick has started to sting more than it should, and you are eyeing your meter with suspicion. Here is the honest truth: when a glucose meter seems to go wrong, it is almost never the meter.
It is the strip that spent an afternoon in a hot car. It is the vial left open on a humid bathroom shelf. It is the lancet on its fortieth use, quietly dull and bent. The device is usually fine. The consumables are where accuracy and comfort actually live, and they are the easiest things in your whole routine to fix.
Get your strips and lancets right and most of the weirdness disappears, along with a good deal of the sting.
Store strips in their original vial with the cap snapped shut, at room temperature, never in a bathroom or car. Respect the expiry date and the discard-after-opening window. Use a fresh lancet every single time, because reused tips dull and hurt. If a reading does not match how you feel, retest with a fresh strip and run a control-solution check. Dispose of used lancets in an approved sharps container through free pharmacy take-back, never the household garbage.
In this article
- How a test strip actually works
- Storing strips so they tell the truth
- Expiry and the discard-after-opening window
- Signs your strips are lying to you
- Lancets are single-use, and here is why it matters
- Sharps disposal in Canada
- A simple supplies-refresh rhythm
- Frequently asked questions
How a test strip actually works
A test strip is not a passive slip of plastic. Each one carries a tiny layer of enzyme chemistry that reacts with the glucose in your blood and turns that reaction into an electrical signal your meter reads as a number.
That enzyme layer is delicate. Three things degrade it: heat, humidity, and time. Heat speeds up the chemistry before you ever draw blood. Humidity creeps in and throws the reaction off. And time simply wears the enzymes down, which is why every vial carries an expiry date.
When the chemistry is compromised, the meter still gives you a confident number. It just is not the right one. The strip cannot tell you it has been damaged, so the burden of protecting it falls on how you store it.
The vial is not just packaging. It is a sealed, dry home that keeps the enzyme chemistry stable.
Storing strips so they tell the truth
The good news is that protecting strips takes no special equipment, just a few habits. Keep these five rules and your strips will behave.
- Leave them in the original vial. The vial holds a desiccant that keeps the inside dry. Loose strips in a pocket, a pill organizer, or a sandwich bag lose that protection immediately.
- Snap the cap shut every time. A cap left ajar lets humidity in overnight. Close it the moment you take a strip out.
- Keep them at room temperature. A drawer, a cupboard, a bedside table: somewhere steady and dry.
- Never the bathroom. The steam from showers is the single worst place for strips. It is warm and humid, which is exactly what the enzymes cannot tolerate.
- Never the car. A glovebox swings from freezing to baking within a day. Do not leave strips there, even overnight.
If you are still learning the whole routine, our beginner's guide to home glucose monitoring walks through the full setup from first prick to logging your numbers.
Expiry and the discard-after-opening window
Every vial of strips has a printed expiry date. Past that date, the enzyme chemistry can no longer be trusted, no matter how carefully you stored the vial. Do not use expired strips to save a few dollars: a wrong number can cost you far more.
There is a second date many people miss. Some strips also carry a discard-after-opening window, meaning you should throw out the vial a set number of months after you first break the seal, even if the printed expiry is further away. Check the label or the insert. If your vial specifies one, write the open date on the vial with a marker so you are never guessing.
Signs your strips are lying to you
Strips fail quietly. They do not crack or change colour. But there are reliable tells that a strip, not your body, is the problem.
| What you notice | What it often means |
|---|---|
| A reading that does not match how you feel | A high number while you feel steady, or a low number with no symptoms, is worth a retest before you act on it |
| Error codes on the meter | Often a damaged, expired, or improperly filled strip rather than a broken device |
| Readings that jump around on the same drop | A sign the strip chemistry may be degraded |
When something looks off, work through it in order: wash and dry your hands first (fruit juice or sugar residue on a fingertip is the classic false high), then retest with a fresh strip from a properly stored vial. If your meter supports control solution, run a control test, which compares a known reference against your strips and meter together. Persistently strange numbers mean it is time to bring your meter and strips to your pharmacy or care team.
Remember that one odd reading is weather, and your overall pattern is climate. Do not overhaul anything on the strength of a single suspicious number. Never adjust your medication or insulin on your own: those numbers belong to a conversation with your care team.
✓ Needs only a tiny drop of blood, so testing stays comfortable
✓ Medical device licensed for Canada, backed by our Toronto team
✗ Store in the original vial and mind the expiry to keep them accurate
Lancets are single-use, and here is why it matters
A lancet looks simple enough that reusing it feels harmless. It is not. A lancet is sterile exactly once, and the tip is precision-ground to slip through skin cleanly on that first use.
Reuse it and two things happen at a microscopic level: the tip dulls, and it bends. A dull, bent tip no longer slices, it tears. That is why the fifth or fortieth prick with the same lancet stings so much more than the first. You are pushing a blunt hook through your skin instead of a clean point. On top of the pain, a used tip is no longer sterile, which raises the risk of infection.
The fix is the least expensive thing in your kit: a fresh lancet every test. While you are at it, rotate your sites. Prick the side of a fingertip rather than the fleshy pad, and move around your fingers so no single spot takes the punishment day after day. Your fingertips will thank you.
✓ Each lancet is individually capped and sealed for single-use hygiene
✓ Fits most standard lancing devices, including the one used with the PPD-400G
✗ Used lancets go in a sharps container, never loose in the garbage
Sharps disposal in Canada
Used lancets are sharps, and in Canada they never belong in your household garbage or recycling. A loose lancet can injure a family member or a waste-handling worker, so disposal follows a simple, safe route.
- Collect them in an approved sharps container. These are the rigid, puncture-resistant bins made for the job. Your pharmacy can supply one.
- Return full containers to a pharmacy. Most provinces run a free take-back program through the Health Products Stewardship Association, so your pharmacy will accept a full container at no charge.
- Never use a household bin. No pop bottles, no jars, no bags. Only an approved container keeps everyone safe.
If you also inject, the same rules cover pen needles. Our guide to insulin pen needle sizes and safe disposal goes deeper on that side of things.
A simple supplies-refresh rhythm
Running out mid-week is stressful and, worse, it tempts people into stretching a lancet or an old strip. A little planning removes the temptation entirely.
Count how many times you test in a normal week, multiply out, and keep at least a month of strips and lancets ahead of that number. Many people reorder both together so the two never fall out of sync. If you are building a full kit from scratch, the Diabetes Care Bundle pairs the monitor, strips, and lancets in one place.
Think of it the way you would any other essential: you refill before the tank hits empty, not after. Fresh supplies are the quiet foundation of numbers you can trust. For more on what to do once you understand your routine, see our practical guide to managing type 2 diabetes at home.
Fresh supplies, numbers you can trust
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Frequently asked questions
Do glucose test strips expire?
Yes. Every vial carries a printed expiry date, and past it the enzyme chemistry can no longer be trusted, even if the strips look fine. Many strips also have a shorter discard-after-opening window, meaning you throw the vial out a set time after breaking the seal. Check the label, and do not use expired strips: a wrong number is not worth the small saving.
Why are my test strips giving different readings?
Usually the strips have been compromised by heat, humidity, or age rather than the meter being broken. Loose strips, a cap left open, or a vial stored in a bathroom or car all degrade the chemistry. Wash and dry your hands, retest with a fresh strip from a properly stored vial, and run a control-solution test if your meter supports it. If odd numbers persist, bring your meter and strips to your pharmacy.
Can you reuse lancets?
No. A lancet is sterile only once, and its tip is precision-ground for a single clean use. Reusing it dulls and bends the tip at a microscopic level, which tears rather than slices the skin, so each prick hurts more, and it also raises the risk of infection. Use a fresh lancet every test and rotate your sites.
How do I dispose of lancets in Canada?
Collect used lancets in an approved, puncture-resistant sharps container, which your pharmacy can supply. When it is full, return it to a pharmacy: most provinces offer free take-back through the Health Products Stewardship Association program. Never put lancets in your household garbage or recycling, and never use a makeshift container like a bottle or jar.
How should I store test strips?
Keep them in their original vial with the cap snapped shut, at a steady room temperature, somewhere dry. Avoid the bathroom (shower steam is the worst offender) and the car (temperatures swing too far). The vial holds a desiccant that keeps the strips dry, so never decant them into another container.
This article is for general education only and is not medical advice. Always work with your diabetes care team on your targets, medications, and monitoring routine.
Diabetes Care Bundle — Glucose Monitor + Test Strips + Lancets
PPD-100 Insulin Pen Needles
PPD-402L Sterile Lancets