Monitoring Your Blood Sugar at Home: How to Choose a Device and Interpret Your Result

A glucose meter (glucometer) is a small, handheld device that people use for blood sugar measurement at home. It requires a tiny drop of blood from a finger to produce real-time results in seconds. 

With advances in technology, continuous glucose monitoring (CGM) has become another option. CGMs are wearable devices that use a sensor under the skin to measure glucose in the body’s tissues 24 hours a day. That’s a huge improvement when compared to traditional glucometers. But how do you choose between the two? And is CGM really necessary for everyone?  

Whichever approach you pick, know this: Experts recommend both traditional glucometers and CGM as daily management tools for anyone with diabetes. When used correctly, and regularly, they can accurately identify out-of-range glucose values and help you reduce the risk of diabetes-related health complications. 

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Blood glucose monitors: What are the options?

Before choosing a device, know your options. Check out the American Diabetes Association’s Consumer Guide to learn about glucometer and CGM choices. You can select those you’re interested in and look at side-by-side comparisons. 

Depending on your health insurance, upfront and ongoing costs of glucometers and CGMs will vary. The good news is most companies give their glucometers away for free. 

Glucometers vs. CGMs

Glucometers and CGMs both measure glucose levels in the body — but that’s where the similarities end. 

A glucometer requires you to prick your finger and catch a drop of blood on a test strip. The device measures your blood glucose level from the test strip — but you have to manually prick your finger and insert the test strip into the machine.  

CGM goes a few steps further. Through a skin sensor, it measures glucose in the body’s tissues. It can take readings continuously, around the clock, and it doesn’t require a needle. 

While both options will tell you what your glucose level is right now, CGM results can have a “lag time.” This means that tissue glucose levels can take a little time to catch up with blood glucose levels. So, even if you’re using a CGM, checking with a glucometer can sometimes be helpful. 

Most people using a CGM also have a glucometer. A glucometer is a helpful backup when:

• The CGM sensor is warming up

• A CGM sensor isn’t working

• The CGM system is calibrating (“resetting”)

• You think the CGM reading might be wrong

Glucometers

A glucometer is a device that checks blood glucose levels from a single drop of blood. It’s up to you how often you do this, but most people with diabetes check their glucose levels three to four times a day. There’s no limit to how often you can use it, but it requires a fresh drop of blood and a fresh test strip every time. 

You’ll get blood glucose results within seconds. So you can know if your glucose is low, high, or within range. Most devices have options to store results over time, making it easy to see patterns and share these with your provider. 

Continuous glucose monitor devices

You can self-insert CGM devices and wear them for up to 14 days. They have three parts:

1. A sensor your wear on the stomach or arm

2. A transmitter to communicate glucose values

3. A receiver (smartphone, insulin pump, or other handheld device)

You’ll “see” your glucose level, and the receiving device will alert you for out-of-range values.

CGMs create a lot of data by reading your glucose every few minutes, all day long. This can give you clues about the following:

• Glucose patterns

• Medication effectiveness

• Sensitivity to exercise

• Response to foods 

They provide a much more accurate picture of how your glucose levels change throughout the day. This is especially useful when you can’t manually check them yourself, such as during exercise or sleep. 

Another benefit is that CGMs can share real-time data with another person. Many CGM users choose to share their CGM data with a family member or friend, so they get alerts, too.

CGMs are more expensive than glucometers, but out-of-pocket costs vary. If you have Medicare, it’s important to understand what’s covered in your plan and what any out-of-pocket costs will be. Affordability and access issues are common challenges people face — even with health insurance. Contact your insurance company to understand what your benefits will cover.

How do I measure my blood sugar? 

You can check your blood glucose with a glucometer in four easy steps:

1. Clean and dry your hands.

2. Place a test strip in the glucometer.

3. Poke your finger with a lancet (or small needle).

4. Apply a drop of blood to the test strip.

How often you test depends on the type of diabetes you have and the medications you take. Your care team will create a diabetes treatment plan that’s best for you. People living with diabetes typically check their glucose at regular times throughout the day:

• First thing in the morning

• Before meals

• Two hours after meals

• At bedtime

• With signs of high or low blood sugar

• During and after exercise

Testing will help you to understand what factors affect your blood glucose. They may include: 

• Physical activity

• Diabetes medications

• Food

• Stress

• Illness

What should my blood sugar levels be?

Glucose values are always changing, but target values stay the same. As a general rule, aim for the American Diabetes Association guidelines, unless your diabetes care team has given you other standards to follow. Targets may vary from person to person, depending on: 

• Age

• Activity level

• Any other health conditions

• Your type of diabetes 

Healthy blood sugar levels for people without diabetes

If you’re over the age of 35, have a high risk for diabetes or symptoms of diabetes, your provider may order testing. You might not have symptoms with prediabetes. This means you may not know you have it unless you get tested. 

Let’s take a look at the fasting (first thing in the morning before you’ve had anything to eat or drink) target numbers:

• Normal: 100 mg/dL or lower

• Prediabetes: 100 mg/dL to 125 mg/dL

• Diabetes: 126 mg/dL or higher

Healthy blood sugar levels for people with diabetes

The ADA sets guidelines for healthy blood glucose targets. When recommending target values, your healthcare provider will consider your personal medical history and other factors.

In general, for an average, nonpregnant adult with diabetes, blood glucose targets fall into these ranges:

• Before meals: 80 mg/dL to 130 mg/dL

• Two hours after starting a meal: 180 mg/dL or lower

• Hemoglobin A1C (HbA1C or A1C): less than 7% 

Your healthcare provider may suggest higher A1C goals if you’re an older adult with multiple medical problems or memory issues. If you’re pregnant, they may suggest lower A1C goals.

How do I track my blood glucose?

Diabetes can be different for each person. By tracking your glucose, you can learn more about your diabetes. 

You can track your glucose by:

• Collecting data from a glucometer or CGM

• Using programs or apps that help to identify patterns

• Taking notes about changes in medications, activity, and foods

At first, you may find yourself reaching out to your diabetes care team more often. But over time, you’ll begin to feel more comfortable tracking and making some changes on your own. 

When you notice patterns with your glucose levels, it’s important to let your diabetes care team know. Don’t wait for your next appointment to share your data. If you’d like them to know about certain glucose patterns, you can share your data at any time. They’ll look at the whole picture and make suggestions on the timing and amounts of medications, exercise, and foods. 

Remember: Diabetes is mostly a self-managed disease. This means that between quarterly visits, you’re doing all of the daily work. 

How do I share my glucose data?

Sharing your glucose data should be a pretty slick and stress-free experience. Start by asking your care team how they prefer to receive it. They have hundreds of people with diabetes sharing data and may have someone to help you.

Many glucometers and CGMs have quick data-sharing solutions. You can upload your CGM or glucometer to programs or apps that generate reports. You can use most of these on a smartphone. There are apps, such as Tidepool, that are compatible with many diabetes devices. These tools allow you to share data and create meaningful insights into your diabetes numbers. 

Focus on the big picture

While it's easy to get caught up in single numbers, it’s important to focus on the big picture. It takes time to become a “diabetes detective,” so be patient with yourself. By using technology to identify patterns and make small adjustments, you’ll learn more about your diabetes in time. 

What affects my blood glucose?

Many things can affect your blood glucose. It’s important to understand what they are, so that you can act and improve the time you spend in your target range. A single number may tell you when you’re in or out of range — but it doesn’t tell you why. 

Again, some factors that affect blood glucose are:

• Illness

• Stress

• Medications

• Physical activity

• Food

Small changes go a long way. Your diabetes care team will guide you on the process. Making adjustments to your daily diabetes routine is specific to you. Get started by checking your glucose before eating and 2 hours after eating. And keep an eye on your glucose during physical activity. This will help you to identify patterns and ways to improve time in range.

Why trust our experts?

Written by:

Jewels Doskicz, RN, BA

Jewels Doskicz, RN, BA, is an Arizona-based registered nurse with 22 years of hospital-wide clinical nursing experience and 11 years of medical writing and editing experience. She was a former healthcare content creator for a digital health tool at HealthLoop and director of clinical content operations at GetWellNetwork.

Edited by:

Sophie Vergnaud, MD

Sophie Vergnaud, MD, is the Senior Medical Director for GoodRx Health. An experienced and dedicated pulmonologist and hospitalist, she spent a decade practicing and teaching clinical medicine at academic hospitals throughout London before transitioning to a career in health education and health technology.

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