Lancets are small, thin needles used to prick your skin and draw a tiny drop of blood for glucose testing. If you have diabetes and monitor your blood sugar at home, lancets are one of the basic supplies you’ll use regularly, often multiple times a day. They fit inside a spring-loaded device that makes the prick quick and controlled.
How Lancets and Lancing Devices Work
A lancet on its own is just a short, disposable needle with a protective cap. You don’t use it by hand. Instead, it loads into a lancing device, which is a pen-shaped tool with a spring mechanism inside. When you press the trigger, the device fires the lancet into your skin at a controlled depth, then retracts it. The whole process takes a fraction of a second.
The puncture creates a small opening in a capillary (a tiny blood vessel near the skin’s surface), producing a drop of blood you can apply to a test strip. That strip goes into your glucose meter, which reads your blood sugar level. The same type of blood sample can also be used to check hemoglobin and other blood components, though glucose monitoring is by far the most common reason people with diabetes use lancets.
Lancet Gauge Sizes
Lancets come in different gauges, ranging from 18G on the thicker end to 33G on the thinnest. The gauge number works in reverse of what you might expect: the higher the number, the thinner the needle. A 33G lancet has a much smaller diameter than a 21G lancet.
Thinner lancets (28G to 33G) are generally less painful, which is why most people doing routine fingerstick testing prefer them. The tradeoff is that a very thin lancet may not produce enough blood for your meter’s test strip, especially if you have thicker skin or calluses from frequent testing. If you’re not getting a large enough drop, you can try a slightly lower gauge before increasing the depth setting on your device.
Reducing Pain During Testing
Most lancing devices let you adjust how deep the needle penetrates. A typical device offers multiple depth settings, sometimes numbered zero through five, with higher numbers pushing the lancet deeper into the skin. Starting at a middle setting (around 3) and adjusting from there is a practical approach. People with thinner skin often do well at lower settings, while thicker or calloused fingertips may need a deeper poke.
A few things make a noticeable difference in comfort. Using a fresh lancet each time is one of the biggest. After even a few uses, the needle tip dulls and the silicone coating that helps it glide through skin wears away. A dull lancet requires more force to penetrate, which means more pain. Washing your hands with warm water before testing also helps: warmth increases blood flow to your fingertips, so you’re more likely to get a good drop from a shallower prick. Pricking the side of your fingertip rather than the pad is another common tip, since the sides have fewer nerve endings.
Alternative Testing Sites
Some glucose meters allow you to test from sites other than your fingertips, including the upper arm, forearm, base of the thumb, or thigh. This can give your fingertips a break if they’re sore from frequent testing.
There’s an important accuracy difference to know about, though. Blood from alternative sites reflects your glucose level with a slight delay compared to fingertip blood. When your blood sugar is changing quickly, such as after eating, after taking insulin, during exercise, or when you’re sick or stressed, alternative sites may give you an outdated reading. The FDA recommends sticking with fingertip testing if you suspect your blood sugar is low, if you don’t usually notice symptoms of low blood sugar, or if an alternative site reading doesn’t match how you feel.
Why Lancets Are Single Use
Lancet manufacturers design them to be used once and discarded. In practice, many people reuse them to save money or out of convenience. If you do reuse lancets, it helps to understand what happens to the needle. The tip becomes progressively duller, typically noticeably so after about five uses. Cleaning the needle with alcohol actually makes this worse because it strips the silicone coating that reduces friction.
Beyond comfort, reuse carries a small infection risk. A used lancet can introduce bacteria into the skin, especially if you notice redness, swelling, or warmth around your testing sites. Each lancet should only ever be used by one person, since sharing lancets creates a risk of transmitting bloodborne infections.
Cost and Insurance Coverage
Lancets are one of the least expensive diabetes supplies. A box of 100 typically costs just a few dollars at most pharmacies, making them significantly cheaper than test strips or continuous glucose monitors. Medicare Part B covers lancets and lancing devices as durable medical equipment supplies. If you use insulin, Medicare allows up to 300 lancets every three months. If you don’t use insulin, the allowance is 100 per quarter. After meeting your Part B deductible, you pay 20% of the approved amount. Most private insurance plans cover lancets as well, though quantities and copays vary.
Safe Disposal of Used Lancets
Used lancets are classified as sharps, the same category as needles and syringes. Tossing them loose in your household trash creates a real risk of needlestick injuries for anyone handling the bag. The FDA recommends placing each used lancet into a sharps disposal container immediately after use. These are rigid, puncture-resistant containers with a secure lid. You can buy FDA-cleared sharps containers at most pharmacies, or use a heavy-duty plastic container like a laundry detergent bottle as a substitute.
Fill your container only to about three-quarters full, then seal it and dispose of it according to your local guidelines. Options vary by location but commonly include drop-off sites at pharmacies or hospitals, household hazardous waste collection events, mail-back programs, and special waste pickup services. Your local health department or trash removal service can tell you which options are available in your area. Never reuse a sharps container once it’s been sealed for disposal, and keep active containers out of reach of children and pets.