Most people with diabetes should test their blood sugar (aka blood glucose) levels regularly. Knowing the results lets you adjust your strategy for keeping the disease in check.
Regular testing can also help you avoid getting long-term health problems that can stem from the condition, like:
- Heart disease
- Stroke
- High blood pressure
- High cholesterol
- Blindness
- Kidney disease
- Skin problems
Research shows that in people with either type 1 or type 2 diabetes, sticking to your target blood sugar and HbA1c levels makes complications less likely.
Ways to Test Your Blood Sugar
Traditional home glucose monitoring
You prick your finger with a small, sharp needle called a lancet, put a drop of blood on a test strip, and then place the strip into a meter that displays your blood sugar levels. Record the test results so you can share them with your doctor. Based on your results, the two of you may adjust your diet, exercise, or medication.
Meters vary in features, portability, speed, size, cost, and readability (with larger displays or spoken instructions if you have vision problems). Devices deliver results in less than 15 seconds and store this information for future use.
Some meters also calculate an average blood sugar level over a span of time. Some also feature software kits that take information from the meter and display graphs and charts of your past test results. Blood sugar meters and strips are available at your local pharmacy.
Meters that test other parts of your body
Some devices let you test your upper arm, forearm, base of the thumb, and thigh.
These results may differ from the blood sugar levels gotten from a fingertip stick. Levels in the fingertips show changes more quickly. This is especially true when your sugar is changing fast, like after a meal or after exercise.
If you have symptoms of low blood sugar, don’t rely on test results from other parts of your body.
Continuous glucose monitoring system
Some of these devices are combined with insulin pumps. They're not as accurate as finger-stick glucose results. But they can help you find patterns and trends in your sugar levels. You may also hear doctors call these “interstitial glucose measuring devices.” If you choose this method, your doctor will place a tiny sensor under your skin to check blood sugar levels every 5 minutes. It sends data to a monitor that you wear like a pager for a few days.
You'll still need to check your levels throughout the day; continuous glucose monitoring doesn't replace that. It gives your doctor more information about trends that self-checking might not show.
When Should I Test My Blood Sugar?
Each person is different. Your doctor will tell you when and how often you should check your levels.
If you use insulin more than once a day or use an insulin pump, experts recommend checking your blood sugar at least three times daily.
What Can Affect My Results?
They may not be accurate if you have anemia or gout. If it’s hot, humid, or you’re at a high altitude, that can interfere with the results, too. So can vitamin C.
If you consistently see results that aren’t expected, recalibrate your meter and check the strips.
The chart below shows you the ideal blood sugar ranges for most adults except for pregnant women. Your ideal range may be different from another person's and will change throughout the day, so check with your doctor for your targets.
Time of Test | Ideal for Adults With Diabetes |
Before a meal | 70-130 mg/dL |
1 to 2 hours after beginning a meal | Less than 180 mg/dL |
Home Blood Sugar Monitoring and HbA1c
Checking your HbA1c level is also important. Many home glucose monitors can display an average blood sugar reading, which correlates to the HbA1c test.
Average Blood Glucose Level (mg/dL) | HbA1c (%) |
125 mg/dL | 6 |
154 mg/dL | 7 |
183 mg/dL | 8 |
212 mg/dL | 9 |
240 mg/dL | 10 |
269 mg/dL | 11 |
298 mg/dL | 12 |
When Should I Call My Doctor?
Ask your doctor about your target blood sugar range. Also, work together to plan for how to handle blood sugar readings that are either too high or too low and when to call your doctor. Learn about the warning signs of high or low blood sugar, and know what you can do if you begin to have symptoms.
Track It Over Time
Keep records of all your test results. Most glucose monitors also have memory for that. Your records can alert you to any problems or trends.
Also, these test records help your doctor make any needed changes in your meal plan, medicine, or exercise program. Bring these records with you to every checkup.
How to Test Your Blood Sugar at Home
Follow these steps:
- Wash and dry your hands well.
- Insert a test strip into your meter.
- Prick the side of your fingertip with the lancet provided with your test kit.
- Gently squeeze or massage your finger until a drop of blood forms.
- Touch and hold the edge of the test strip to the drop of blood.
- The meter will display your blood glucose level on a screen after a few seconds.
Why You Should Check Your Blood Sugar
Testing blood glucose can help you manage diabetes by showing you:
- How well your diabetes treatment plan is working
- How exercise and food affect your blood sugar levels
- How things like stress and illness affect your levels
- How well your diabetes medication is working
- When your blood sugar levels are too high or too low
Who Should Check Their Blood Sugar?
You’ll need to test your levels if you’re:
- Taking insulin
- Pregnant
- Having a hard time controlling blood glucose levels
- Having low blood glucose levels, especially without warning signs
- Have ketones from high blood glucose levels
When Should You Test Your Blood Sugar?
It depends on which type of diabetes you have:
- Type 1 diabetes. It’s up to your doctor. They could suggest you test anywhere between four and 10 times a day. For example, you could test before meals and snacks, before and after exercise, before bed, and even during the night. You may also need to check more often if you’re sick, making changes to your daily routine, or starting a new medication.
- Type 2 diabetes. It depends on what you take to treat your diabetes:
- Insulin. The doctor may tell you to test a few times a day, depending on the type and amount of insulin you use. You’ll probably test before meals and at bedtime if you're taking multiple daily injections. You may need to test only twice daily, before breakfast and dinner, if you only use a long-acting insulin.
- Medications. If you use drugs to manage diabetes, your doctor will tell you how often to check your blood sugar.
- Lifestyle changes. If you’re relying on diet and exercise, you may not need to test your blood sugar daily.