Blood Sugar Monitoring: What You Need to Know

Blood Sugar Monitoring: What You Need to Know
18.01.2024

Blood sugar monitoring is one of the most important aspects of managing diabetes, especially for people who have type 1 diabetes and those who take insulin. You can check your blood sugar by using a glucose meter and test strips or a CGM system. Your healthcare provider will help you determine how often and when you should check your blood sugar.

Why should I monitor my blood sugar?

If you have diabetes, monitoring your blood sugar (glucose) is key to finding out how well your current treatment plan is working. It gives you information on how to manage your diabetes on a daily — and sometimes even hourly — basis.

Monitoring your blood sugar is important when you have diabetes, especially if you use insulin. The results of blood sugar monitoring can help you make decisions about food, physical activity and dosing insulin.

Several things can affect your blood sugar. You can learn to predict some of these impacts with time and practice, while others are very difficult or impossible to predict. That’s why it’s important to check your blood sugar regularly if your healthcare provider recommends doing so.

For example, the following situations typically raise blood sugar levels:

  • Consuming carbohydrates.
  • Not taking enough diabetes medication or insulin or missing a dose.
  • Consistent lack of exercise or getting less activity than you usually do.
  • Taking corticosteroid (steroid) medications.
  • Illness, surgery or stress.
  • Dawn phenomenon (an early-morning rise in blood sugar that’s likely due to natural fluctuations in hormones, such as cortisol).
  • Smoking.
  • Dehydration.
  • Puberty.

The following situations typically lower your blood sugar:

  • Missing meals.
  • Taking too much diabetes medication or insulin.
  • Physical activity.

The following situations can raise and/or lower your blood sugar depending on other factors and your unique biology:

  • Periods (menstruation).
  • Food and medication/insulin timing.
  • Drinking beverages containing alcohol.
  • Non-diabetes medication interactions.

Due to all of these varying factors, it’s essential to monitor your blood sugar if you have diabetes. It’s the only way to know for sure when your blood sugar levels are changing. And it helps you and your healthcare provider know how to adjust your management.

How can I monitor my blood sugar at home?

There are two main ways you can monitor your blood sugar at home if you have diabetes:

  • With a glucose meter and finger stick.
  • With a continuous glucose monitor (CGM).

You may choose either or both methods for a variety of reasons, such as:

  • Your access to the technology, which can vary due to cost and medical insurance coverage.
  • What form of diabetes you have.
  • How often your healthcare provider recommends checking your blood sugar.
  • Your overall health.

Glucose meters and test strips

The most common type of blood sugar monitoring involves using a glucose meter and test strips. This is a “finger stick check.” You prick your fingertip with a small needle called a lancet to produce a blood drop. You then place the drop against the test strip in the glucose meter, and the meter shows your blood sugar level within seconds.

Finger stick checks only measure blood glucose at one moment in time, so people with diabetes, especially those taking insulin, often have to check their blood sugar several times a day using this method.

Glucose meters and test strips are available at your local pharmacy, through mail order or through your healthcare provider. There are many different types of glucose meters. Your healthcare provider can help you select the meter that’s best for you.

If you have medical insurance, check with your insurance company to see if they cover glucose meters and test strips. Some insurances only cover certain brands. If you don’t have insurance, check with your provider for other options.

CGMs

CGM involves wearing a device that measures your glucose levels 24 hours a day. The device uses this data to form a graph that shows a more complete picture of how your blood sugar levels change over time.

Most CGM devices use a tiny sensor that you insert under your skin. The sensor measures glucose levels in the fluids between your body’s cells (interstitial fluid).

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There are a few different types and brands of CGMs. Some CGMs link to specific insulin pumps. Others operate independently. Most CGMs can send alarms or alert messages when they detect low or high glucose levels.

Like all technology, CGMs can sometimes fail or be inaccurate. So, don’t completely rely on CGMs without finger stick checks, especially if your CGM readings don’t match the symptoms of low or high blood sugar you’re experiencing, or if your CGM gives you an error message.

Ask your healthcare provider about CGM options if you’re interested in using this technology. You’ll also need to check with your insurance company to see if they cover the costs and which brands they cover.

Tracking blood sugar levels

Most glucose meters allow you to save the results. You may be able to use an app on your smartphone to track your levels. If you don’t have a smartphone, keep a written record of your blood sugar levels that includes the date, time of the test and any other details, like if it was before or after a meal. You should bring your glucose meter, phone or written record with you each time you visit your healthcare provider.

CGM systems save the data of your glucose levels. Your provider will be able to access the information.

Procedure Details

How do I check my blood sugar?

In general, to check your blood sugar with a glucose meter, you’ll:

  1. Wash your hands. If you have food debris on your fingers, for example, it can affect the result of the test. If you can’t wash with soap and water, use an alcohol wipe on your fingertip.
  2. Insert a test strip into your glucose meter.
  3. Use a lancing device to prick the side of your fingertip to get a drop of blood. You may need to squeeze your finger to produce more blood or prick a different finger if you can’t get enough blood.
  4. Touch and hold the edge of the test strip against the drop of blood and wait for the result. Your blood glucose level will appear on the meter’s screen.

All glucose meters are slightly different. Always refer to the user’s manual for specific instructions.

All CGM devices function differently as well. If you have a CGM, you’ll receive training on how to insert the sensor and use the system.

How often should I check my blood sugar?

How often you should check your blood sugar depends on what type of diabetes you have and other factors, like the diabetes medicines you take, your overall health and the demands of your daily life. Your healthcare provider will give you suggestions for how often you should check.

You may benefit from more regular blood sugar monitoring if you:

  • Take insulin.
  • Are pregnant.
  • Are having difficulty reaching your blood glucose targets.
  • Have frequent low blood sugar episodes.
  • Have low blood glucose levels without experiencing the usual warning signs.
  • Are sick.
  • Just had surgery.

When should I check my blood sugar?

Your healthcare provider will give you suggestions for the best times to check your blood sugar. This will vary from person to person.

It’s especially important to check your blood sugar when you experience symptoms of low or high blood sugar.

There are also some general guidelines about which times of the day are most beneficial to check your blood sugar to assess how well your management plan is working.

Low blood sugar

Most people with diabetes have symptoms of low blood sugar (hypoglycemia) when their blood sugar is less than 70 mg/dL (milligrams per deciliter). When your blood sugar is low, your body gives out signs that you need food.

Common early symptoms of low blood sugar include:

  • Weakness.
  • Dizziness.
  • Intense hunger (polyphagia).
  • Trembling and feeling shaky.
  • Sweating.
  • Pounding heart.
  • Feeling frightened or anxious.

When you have these symptoms, it’s important to check your blood sugar to see if your levels are low and how low they are. This will inform how you treat the low blood sugar.

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You need to consume carbohydrates (sugar), like a banana or apple juice, to treat hypoglycemia. Severe hypoglycemia can be life-threatening.

High blood sugar

For people with diabetes, healthcare providers usually consider blood sugar levels above 180 mg/dL to be high blood sugar (hyperglycemia). However, most people with diabetes don’t feel symptoms of high blood sugar until their level is 250 mg/dL or higher.

High blood sugar can be dangerous to your health in the short term and long term, so it’s important to check your blood sugar if you’re experiencing the following symptoms:

  • Increased thirst (polydipsia) and/or hunger.
  • Frequent urination (peeing).
  • Headache.
  • Irritability.
  • Blurred vision.

If you take insulin, you’ll need to treat the high blood sugar with insulin according to your healthcare provider’s instructions. If you have symptoms of diabetes-related ketoacidosis (DKA), such as those of high blood sugar with vomiting and fatigue, call your provider immediately. DKA is a life-threatening complication and needs immediate treatment.

Blood sugar monitoring during the day

Certain times of the day are most helpful to check your blood sugar to assess your overall diabetes treatment plan, especially if you take insulin. These times include:

  • When you wake up: Your blood sugar level at this time is known as fasting glucose. It can help assess how your blood sugar levels are overnight, especially if you also check your blood sugar before you go to bed.
  • Before meals: Checking your blood sugar before meals can help you plan your meal. If you take insulin, checking before a meal helps you to know how to dose for it. Checking before and after meals also helps you and your provider assess how food affects your blood sugar.
  • After meals: Checking your blood sugar two hours after you start your meal can help you and your provider assess how food affects your blood sugar and if you need to change your insulin or medication doses. It’s common to experience high blood sugar after eating, especially if you need to take insulin.
  • Before and after exercise: Checking your blood sugar before and after exercise can help you and your provider assess how that type of activity affects your blood sugar. Exercise typically lowers your blood sugar but it could also increase it, so checking afterward can help catch these episodes.
  • Before you go to sleep: Checking your blood sugar before you go to sleep can catch potential low or high blood sugars. If you experience low blood sugar while you’re sleeping, it can be more dangerous because you might not wake up right away from the symptoms. Consistently going to sleep with high blood sugar can be harmful to your health over the long term, because it’ll likely be elevated for several hours while you’re sleeping.

What is the target range for blood sugar?

If you have diabetes, your target range for blood sugar levels is unique to you. Together, you and your healthcare provider will decide the target range that’s ideal for you. This will likely change throughout your life.

Blood glucose targets vary based on:

  • How long you’ve had diabetes.
  • Your age and life expectancy.
  • Certain conditions you may have that affect blood sugar, such as Cushing syndrome or gastroparesis.
  • If you have cardiovascular disease.
  • If you have diabetes complications, like neuropathy, retinopathy or nephropathy.
  • If you have hypoglycemia unawareness (not experiencing symptoms of low blood sugar).
  • If you’re pregnant or trying to become pregnant.
  • Your access to diabetes medications and management technology.

In general, the American Diabetes Association suggests the following targets for most nonpregnant adults with diabetes:

  • Before a meal: 80 to 130 mg/dL.
  • One to two hours after the beginning of the meal: Less than 180 mg/dL.

Your provider may also have specific targets for your fasting blood glucose (your blood sugar when you first wake up in the morning) and for before you go to sleep.

Risks / Benefits

What are the benefits of monitoring my blood sugar?

Regular blood sugar monitoring is one of the most important things you can do to manage diabetes. You’ll be able to see what makes your levels go up or down, such as eating different foods, taking your medicine/insulin or exercising.

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Diabetes affects everyone differently, so there’s no “one-size-fits-all” approach to management. The information you gather by checking your blood sugar helps you and your healthcare team make decisions about the best treatment plan for you. These decisions can help delay or prevent diabetes complications and help you live a healthy life.

What are the risks of monitoring my blood sugar?

The possible risks or “cons” of blood sugar monitoring include:

  • Pain from fingertip pricking or CGM insertions.
  • Cost.
  • Experiencing negative emotions.

Fingertip pain

Frequent fingertip pricking can make your fingertips sore. The good news is that a few things can help alleviate this:

  • Be sure to prick your fingertips on the side as opposed to in the middle of them. You have more nerve endings in the center of your fingertips, so pricking them there can be more painful.
  • Changing your lancet frequently can help reduce fingertip soreness. The more you reuse a single lancet, the duller it becomes. This can make finger pricks more painful.
  • Newer test strips require smaller amounts of blood than they used to. This means you may not have to prick your finger as “deep” as people with diabetes once needed to.
  • Newer types of lancets and lancing devices can also help reduce the amount of pain or soreness you experience.
  • Some glucose meters allow you to prick other parts of your body, such as your palms or forearms.

Talk to your provider if you’re experiencing fingertip pain from blood sugar monitoring. They can help you find alternative devices and options.

Cost

Test strips for blood sugar monitoring and CGM systems can be expensive. And medical insurance coverage for test strips and CGMs can vary significantly in the United States.

If you can’t afford test strips, talk to your provider. They may be able to help you find resources to lower the cost of test strips. For example, some pharmacies offer coupons. There may also be groups or programs in your community that help with diabetes testing supplies.

Negative emotions

Blood sugar results can trigger strong feelings. It’s common to feel frustrated, confused, angry or upset about diabetes and its management.

It’s important to remember that blood sugar numbers are just that — numbers. They’re not a “grade” or a moral judgment. There are so many things that can affect blood sugar — many of which are difficult or impossible to anticipate. Know that monitoring your blood sugar levels is simply a tool for checking how well your current treatment plan is working. And it can be very helpful for making changes to your plan.

If you’re experiencing frequent negative thoughts and emotions about diabetes, talk to your provider or consider seeing a mental health professional, such as a psychologist or therapist. It’s common for people with diabetes to have depression and/or anxiety. You’re not alone.

When to Call the Doctor

When should I call my healthcare provider about my blood sugar level?

If you’re experiencing high or low blood sugar levels and/or symptoms frequently — whether you have type 1 diabetes or type 2 diabetes — talk to your provider. They’ll likely recommend adjustments to your diabetes management plan.

When should I seek emergency care?

If you have symptoms of diabetes-related ketoacidosis, call your provider immediately or go to the nearest emergency room.

If a loved one has severe low blood sugar and is unresponsive or unconscious, call 911.

What should I ask my provider about blood sugar monitoring?

It may be helpful to ask your diabetes healthcare provider the following questions about blood sugar monitoring:

  • What’s my target blood sugar range? Why is that the target for me?
  • How often should I check my blood sugar?
  • Do you recommend using a glucose meter or a CGM for blood sugar monitoring?
  • What do different blood sugar levels mean?
  • What changes should we make to my treatment plan?

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