Monitoring blood sugar means checking your glucose levels at regular intervals using a fingerstick meter, a continuous glucose monitor (CGM), or both. The method and frequency that work best depend on your type of diabetes and how you manage it. People on intensive insulin therapy may need to check 4 to 10 times a day, while those managing type 2 diabetes with non-insulin medications may not need daily checks at all.
Fingerstick Meters: The Standard Method
A blood glucose meter gives you a snapshot of your blood sugar at the moment you test. You prick the side of your fingertip with a small lancet, place a drop of blood on a test strip, and the meter displays your reading within seconds. Modern meters that meet international accuracy standards must produce at least 95% of readings within 15% of laboratory values when blood sugar is 100 mg/dL or above, and within 15 mg/dL when levels are below 100 mg/dL. That’s accurate enough to guide day-to-day decisions, but it means occasional readings can be slightly off.
A few practical steps improve your results. Wash your hands with warm water and soap before testing. Residue from food or lotion on your fingers can skew readings. Use a fresh lancet each time, as reused lancets dull quickly and make the stick more painful. Most lancing devices let you adjust the depth setting; start shallow and increase only if you’re not getting enough blood. Prick the side of your fingertip rather than the pad, where nerve endings are more concentrated.
When and How Often to Test
If you have type 1 diabetes, expect to test 4 to 10 times a day or use a CGM. Common testing times include before each meal, before bed, before exercise, and whenever you feel symptoms of a low or high. If you take multiple daily insulin injections for type 2 diabetes, testing before meals and at bedtime is typical. People on a single injection of long-acting insulin often only need to check before breakfast and occasionally before dinner.
If you manage type 2 diabetes without insulin, your doctor may recommend periodic checks rather than daily monitoring. The goal in that case is usually to confirm that your current treatment plan is working, not to make real-time dosing decisions.
Checking after meals matters too. Post-meal blood sugar peaks about one to two hours after you start eating, so that’s the window to test if you want to see how a specific food affects you. The target for most adults with diabetes is below 180 mg/dL at that post-meal peak.
Target Ranges to Know
The American Diabetes Association’s 2025 guidelines set these targets for most nonpregnant adults with diabetes:
- Before meals: 80 to 130 mg/dL
- One to two hours after starting a meal: below 180 mg/dL
These are general goals. Your personal targets may be tighter or more relaxed depending on your age, how long you’ve had diabetes, your risk of low blood sugar, and other health conditions. Older adults or people at higher risk of hypoglycemia are often given wider ranges to reduce the chance of dangerous lows.
Continuous Glucose Monitors
A CGM is a small sensor inserted just under your skin, typically on the back of your arm or your abdomen. It measures glucose in the fluid between your cells (called interstitial fluid) every few minutes and sends readings to your phone or a receiver. Instead of isolated snapshots, you get a continuous line showing trends, direction, and speed of change throughout the day and night.
One thing to understand: glucose reaches your bloodstream first and then filters into interstitial fluid. This creates a lag of a few minutes between a CGM reading and a traditional fingerstick. During times when blood sugar is changing rapidly, like right after a meal or during exercise, the CGM reading may trail behind your actual blood sugar. Most modern sensors are accurate enough for daily decision-making, but some situations still call for a confirming fingerstick, particularly if your symptoms don’t match what the sensor shows.
CGMs are especially useful for spotting patterns that fingerstick testing misses. You can see overnight lows you’d sleep through, post-meal spikes from specific foods, and the effect of stress or exercise on your levels in real time. Many systems include customizable alerts that warn you before you go too high or too low.
Time in Range: A Better Way to Track Progress
If you use a CGM, one of the most useful metrics is “Time in Range,” or TIR. This tells you what percentage of the day your blood sugar stays between 70 and 180 mg/dL. An international consensus panel recommends that most adults with type 1 or type 2 diabetes aim to spend more than 70% of the day in that range, which works out to roughly 16 hours and 48 minutes. For older adults or those at higher risk, the goal is more than 50%, or about 12 hours a day.
What makes TIR especially motivating is that even small improvements matter. Each additional 5% of time spent in range is associated with meaningful health benefits. So moving from 55% to 60% is a real win, even if you’re not yet at the 70% target. TIR gives you a more complete picture than a single fasting reading ever could, because it captures the full 24-hour story of your glucose control.
Automated Insulin Delivery Systems
The latest step in monitoring technology pairs a CGM with an insulin pump in what’s called a hybrid closed-loop system. The CGM continuously feeds glucose data to the pump, which uses an algorithm to adjust insulin delivery automatically. The system increases insulin when glucose is rising and reduces or suspends it when levels are dropping. You still need to enter information about meals and confirm certain doses, but much of the day-to-day adjustment happens without your input. These systems are primarily used for type 1 diabetes and have been shown to improve time in range while reducing both highs and lows.
Smartwatches and Non-Invasive Devices
You may have seen smartwatches or smart rings that claim to measure blood sugar without piercing the skin. The FDA has issued a direct safety warning about these products: no smartwatch or smart ring has been authorized, cleared, or approved by the FDA to measure or estimate blood glucose levels on its own. The agency warns that using these devices could lead to inaccurate readings, which is dangerous if you rely on them to make treatment decisions. This applies regardless of manufacturer or brand. If a wearable claims to track blood sugar without a sensor under your skin, treat that claim with serious skepticism.
Making Sense of Your Numbers
Raw numbers don’t help much unless you look for patterns. Keep a log, whether it’s a written notebook, a meter’s built-in memory, or an app that syncs with your CGM. Note what you ate, when you exercised, how you slept, and anything unusual like illness or stress. After a week or two, patterns tend to emerge: maybe your levels spike after breakfast but stay steady after dinner, or maybe you consistently go low during afternoon workouts.
Those patterns are what allow you and your healthcare team to make targeted changes, whether that means adjusting a medication dose, shifting the timing of a meal, or changing what you eat before exercise. Monitoring without reviewing the data is like stepping on a scale every day but never looking at the trend. The value is in what you do with the information, not just in collecting it.