You can check your blood sugar at home using a small portable device called a glucometer, which reads a drop of blood from your fingertip and displays your glucose level in seconds. For ongoing tracking without finger pricks, continuous glucose monitors (CGMs) measure your levels automatically throughout the day. Clinical lab tests ordered by your doctor provide a longer-term picture of blood sugar control. Here’s how each method works and what you need to know to get accurate results.
Using a Glucometer at Home
A glucometer (also called a blood glucose meter) is the most common way people check their blood sugar. The device is small enough to fit in a pocket, and each test takes under a minute. You’ll need three supplies: the meter itself, disposable test strips designed for that specific meter, and a lancing device with small disposable needles to prick your finger.
The process is straightforward:
- Wash your hands with soap and warm water, then dry them completely. Don’t use hand sanitizer, as residue on your skin can throw off the reading.
- Insert a test strip into the meter.
- Massage or shake your hand to increase blood flow to your fingertip.
- Use the lancing device to prick the side of your fingertip.
- Squeeze gently from the base of your finger to form a drop of blood, then touch it to the test strip.
- Wait a few seconds for the reading to appear on the screen.
- Record the result, along with any notes about what you ate, your activity level, or anything else that might have affected the number.
If your hands are cold, blood flow to your fingertips slows down, making it harder to get enough blood on the strip. Warming your hands before washing them helps. Apply one generous drop of blood the first time. Adding more blood to the strip after the initial drop can produce an inaccurate reading.
When to Test for the Best Information
The timing of your test matters as much as the test itself, because blood sugar fluctuates throughout the day based on meals, exercise, stress, and sleep. Your testing schedule depends on your type of diabetes and treatment plan.
If you have type 1 diabetes, testing 4 to 10 times a day is typical. That usually means checking before meals and snacks, sometimes after meals, before and after exercise, and before bed. For type 2 diabetes managed with multiple daily insulin injections, testing before meals and at bedtime is common. If you take a longer-acting insulin once or twice a day, you may only need to test before breakfast and occasionally before dinner or bedtime. Your doctor can help you nail down the schedule that gives you the most useful data.
Continuous Glucose Monitors
A CGM eliminates most finger pricks by measuring glucose levels around the clock. A tiny sensor sits just under your skin, usually on your belly or the back of your arm, and reads glucose in the fluid between your cells (called interstitial fluid) rather than directly in your blood. The sensor transmits readings to a receiver or your phone, giving you a real-time picture of your levels and how they trend up or down over hours.
CGMs are especially useful for spotting patterns that finger-prick testing can miss, like overnight drops or post-meal spikes you wouldn’t catch with a few daily checks. Most sensors last 10 to 14 days before you replace them. Some systems still recommend occasional finger-prick tests to confirm the CGM’s accuracy, particularly if a reading doesn’t match how you feel.
A newer option, the Biolinq Shine, received FDA clearance in September 2025 as the first wearable glucose sensor that doesn’t require any needle for placement. It uses a microsensor array on the forearm that sits up to 20 times more shallow than conventional CGM sensors. A color-coded light on the patch itself tells you whether your glucose is in range without needing to pull out your phone. It’s designed for people with diabetes who don’t use insulin.
Lab Tests That Show the Bigger Picture
Home monitoring tells you what your blood sugar is doing right now. Lab tests ordered by your doctor reveal how well your blood sugar has been controlled over weeks or months. The two most common are the A1C test and the fasting plasma glucose test.
The A1C test measures the percentage of your red blood cells that have glucose attached to them. Because red blood cells live about three months, the result reflects your average blood sugar over that period. It’s a single blood draw, no fasting required, and it’s the standard test for diagnosing diabetes and tracking long-term management. A fasting plasma glucose test measures your blood sugar after you haven’t eaten for at least eight hours, giving your doctor a snapshot of your baseline level.
These two tests don’t always tell the same story. Factors beyond blood sugar, including ethnicity and certain blood conditions, can shift A1C results relative to actual glucose levels. When the numbers disagree, doctors sometimes use an oral glucose tolerance test, where you drink a sugary solution and have your blood drawn at timed intervals to see how your body processes glucose.
What Causes Inaccurate Readings
A reading that seems off isn’t always a sign that something is wrong with your health. Several common issues can skew your glucometer results.
Expired or damaged test strips are one of the most frequent culprits. Strips are sensitive to moisture and heat, so store them in their sealed container and check the expiration date before using them. Always make sure the strips are designed for your specific meter, since strips from different brands aren’t interchangeable.
Dirty or damp skin at the test site can contaminate the blood sample. Soap and water work best for cleaning. If you use an alcohol wipe, let the skin dry completely before pricking it.
Dehydration and anemia both affect accuracy. When you’re dehydrated, the concentration of your blood changes, which can push readings higher than your actual glucose level. A low red blood cell count (anemia) can also distort results.
Testing site matters too. Some meters allow you to test on your forearm or palm instead of your fingertip, but those alternate sites are less accurate when your blood sugar is changing quickly, like right after a meal or during exercise. If a reading from an alternate site seems wrong, retest with a fingertip sample.
Cost and Supply Basics
Glucometers are relatively inexpensive, often under $30, but test strips are the ongoing cost. You’ll go through them quickly depending on how often you test. Medicare covers testing supplies with limits based on your treatment: up to 300 test strips per three-month period if you use insulin, or up to 100 strips per three months if you don’t. Most private insurance plans cover supplies as well, though copays vary. CGMs cost more upfront but are increasingly covered by insurance, particularly for people on insulin.
Keep a stock of lancets and strips so you’re never caught without them, and check strip expiration dates when you buy in bulk. Running out of supplies or using expired strips are two of the simplest problems to avoid and two of the most common reasons people fall behind on monitoring.