People with diabetes check their blood sugar using one of two main tools: a handheld blood glucose meter (glucometer) that tests a small drop of blood, or a continuous glucose monitor (CGM) that reads sugar levels automatically through a tiny sensor worn on the body. Most people use one or both depending on their type of diabetes, their treatment plan, and what their insurance covers. A third tool, the A1c test, measures long-term blood sugar averages but isn’t used for daily monitoring.
Blood Glucose Meters
A blood glucose meter, or glucometer, is the most common and affordable way to check blood sugar. You prick your fingertip with a small spring-loaded device called a lancet, place a drop of blood on a disposable test strip, and insert the strip into the meter. Within a few seconds, the screen displays your blood sugar level in milligrams per deciliter (mg/dL). The whole process takes under a minute.
Most meters store hundreds of readings with timestamps so you can spot patterns over days or weeks. Many also connect to smartphone apps that let you log meals, medications, and activity alongside your numbers, then share reports with your doctor. Popular systems include the OneTouch Verio, Contour Next, and Accu-Chek Guide, though dozens of brands exist at varying price points.
Fingertips are the standard testing site because blood flow there reflects your current sugar level most accurately. Some meters also allow testing on the palm, forearm, upper arm, or thigh. These alternative sites hurt less, but they lag behind fingertip readings when blood sugar is changing quickly. If you’ve just eaten, exercised, taken insulin, or feel unwell, stick with fingertips. Alternative site testing is also not recommended during pregnancy.
Continuous Glucose Monitors
A CGM is a small wearable sensor, roughly the size of two stacked quarters, that you apply to your upper arm or abdomen. A hair-thin filament sits just beneath the skin and measures glucose in the fluid surrounding your cells (called interstitial fluid) every few minutes. A transmitter sends those readings wirelessly to your phone or a dedicated receiver, giving you a real-time number and a trend arrow showing whether your sugar is rising, falling, or holding steady.
Because glucose reaches your bloodstream before it seeps into the surrounding fluid, CGM readings run a few minutes behind a fingerstick. That small delay rarely matters in practice, but it’s worth knowing if your number and how you feel don’t quite match up.
Leading CGM Systems
The two most widely used CGMs right now are the Dexcom G7 and the FreeStyle Libre 3. The Dexcom G7 sensor lasts 10 days, warms up in 30 minutes after you apply it, and starts transmitting automatically. It also offers a 12-hour grace period after the 10 days expire, so you have some flexibility on when you swap sensors. The FreeStyle Libre 3 lasts 14 days but takes 60 minutes to warm up and begins its session when you scan it with your phone.
Both systems send continuous readings to a smartphone app without requiring routine fingerstick calibrations. Both can be set to alert you when your sugar drops too low or climbs too high, which is especially valuable overnight.
Over-the-Counter CGMs
In 2024, the FDA cleared the first CGM available without a prescription: the Dexcom Stelo. It’s designed for adults 18 and older who do not use insulin and don’t have a history of dangerous low blood sugar episodes. The Stelo pairs with a smartphone app and works like other CGMs, continuously measuring and displaying glucose values. This opens the door for people with prediabetes or early type 2 diabetes to track how food, sleep, and exercise affect their sugar without needing a doctor’s order.
How A1c Tests Fit In
While meters and CGMs capture what your blood sugar is doing right now, the hemoglobin A1c test reflects your average blood sugar over the past two to three months. It’s typically done as a lab blood draw at your doctor’s office a few times per year. The result comes back as a percentage: below 5.7% is considered normal, 5.7% to 6.4% indicates prediabetes, and 6.5% or above points to diabetes.
At-home A1c kits do exist, but their accuracy is limited. Studies comparing point-of-care A1c devices to certified laboratory tests have found that the at-home versions tend to read lower than the lab. In one study, roughly 18% of people whose lab A1c was above 7% got a result below that threshold on their home device, potentially masking inadequate blood sugar control. The FDA has stated that over-the-counter A1c tests should not be used to diagnose diabetes. They can offer a rough check between doctor visits, but they shouldn’t replace lab testing when decisions about treatment are on the line.
Apps and Data Sharing
Nearly every modern meter and CGM pairs with a companion app that does more than just display numbers. These apps generate charts, calculate averages, estimate time spent in your target range, and flag patterns you might miss on your own. Several platforms also let you share data directly with your healthcare team or family members.
LibreView syncs data from FreeStyle devices to an online dashboard your doctor can review between appointments. Glooko pulls data from multiple brands of meters and CGMs into one place. The Tidepool app consolidates information from various diabetes devices into a single view. CareLink Connect lets a caregiver monitor CGM data for up to five people. OneTouch Reveal syncs meter readings and lets you invite care partners to follow along. For parents of children with diabetes or partners who want to keep an eye on overnight lows, these follower features provide real peace of mind.
Insurance Coverage for CGMs
CGM sensors and transmitters cost significantly more than traditional test strips, so insurance coverage matters. Medicare covers continuous glucose monitors if you take insulin or have a documented history of problematic low blood sugar, and if you or your caregiver have completed training on how to use the device. Most private insurers follow similar criteria, though specifics vary by plan. If you use a meter-only setup, test strips are generally covered more broadly, though the number of strips per month your plan allows can differ depending on whether you’re on insulin.
Choosing Between a Meter and a CGM
For someone on multiple daily insulin injections or an insulin pump, a CGM is often the more practical choice. The continuous data stream helps you adjust doses in real time, catch lows before they become dangerous, and see exactly how meals and activity shift your numbers throughout the day. Many people on insulin still keep a meter as a backup for moments when a CGM reading seems off or a sensor has expired.
If you manage type 2 diabetes with oral medications or lifestyle changes alone, a basic glucose meter may be all you need. Testing a few times a day, or even a few times a week, can give you enough information to understand which foods spike your sugar and whether your overall management is working. The over-the-counter Stelo CGM now offers a middle ground: continuous data without a prescription, aimed at people who want more insight but don’t need the medical-grade alarms and insulin integration of a full CGM system.
Cost, comfort, and lifestyle all play a role. Some people prefer the simplicity and low expense of a meter. Others find that wearing a sensor and checking a phone is far less disruptive than pricking a finger several times a day. Both approaches give you the same core information: a number that tells you where your blood sugar stands so you can make informed choices about food, activity, and medication.