What Is a Normal Blood Sugar Level and How Do I Test It?

17 Sep 2025 By Stephen M. McMullan, M.D.

What Is a Normal Blood Sugar Level and How Do I Test It?

Maintaining normal blood sugar levels is crucial for overall health and well-being. Unregulated blood sugar can lead to various health complications, including diabetes, heart disease, and kidney problems. Understanding what constitutes a normal range and how to monitor your levels empowers you to take proactive steps in managing your health. This article will cover everything you need to know about normal blood sugar, how to test it, and what to do if your levels are outside the healthy range.

Why Blood Sugar Levels Matter

Blood sugar, or glucose, is the primary source of energy for the body's cells. It comes from the food you eat. Insulin, a hormone produced by the pancreas, helps glucose from food get into your cells to be used for energy. When blood sugar levels are consistently too high (hyperglycemia) or too low (hypoglycemia), it can indicate an underlying health problem, most commonly diabetes.

Hyperglycemia (High Blood Sugar): Occurs when there isn't enough insulin or when the body can't use insulin properly. Prolonged high blood sugar can damage organs and tissues.
Hypoglycemia (Low Blood Sugar): Occurs when there is too much insulin or not enough glucose in the bloodstream. Low blood sugar can lead to dizziness, confusion, and, in severe cases, loss of consciousness.

Knowing and managing your blood sugar levels helps you prevent or manage these conditions, reducing the risk of long-term health complications. Fasting Blood Glucose How To Prepare For An Accurate Reading

Understanding Normal Blood Sugar Levels

Normal blood sugar levels vary depending on the time of day and whether you've recently eaten. Healthcare professionals typically use specific ranges for fasting blood sugar (measured after at least eight hours of not eating) and postprandial blood sugar (measured two hours after eating).

General Guidelines for Normal Blood Sugar Levels:

The following table provides a general guide to target blood sugar levels for adults without diabetes, as recommended by major health organizations:

Fasting Blood Sugar: A reading between 70 and 99 mg/dL is generally considered normal. A fasting blood sugar level of 100 to 125 mg/dL indicates prediabetes, while 126 mg/dL or higher indicates diabetes.
Postprandial Blood Sugar: Two hours after eating, a blood sugar level below 140 mg/dL is considered normal. A reading between 140 and 199 mg/dL suggests prediabetes, and 200 mg/dL or higher indicates diabetes.
HbA1c (Hemoglobin A1c): This test provides an average of your blood sugar levels over the past 2-3 months. An A1c level below 5.7% is considered normal, between 5.7% and 6.4% indicates prediabetes, and 6.5% or higher indicates diabetes.

Important Note: These are general guidelines and may vary based on individual health conditions or as advised by your healthcare provider. Factors such as age, medical history, and other health conditions can influence what is considered a normal range for you.

Blood Sugar Levels for People with Diabetes

For individuals diagnosed with diabetes, the target ranges are typically different to help manage the condition effectively:

Fasting Blood Sugar: The ADA generally recommends a target fasting blood sugar level of 80-130 mg/dL for people with diabetes.
Postprandial Blood Sugar: A target of less than 180 mg/dL two hours after eating is typically advised.
HbA1c: Many healthcare providers aim for an A1c level below 7.0% to reduce the risk of diabetes complications.

Regular monitoring and adjustments to medication, diet, and exercise are crucial for maintaining these target levels.

How to Test Your Blood Sugar

Monitoring your blood sugar levels regularly is essential, especially if you have diabetes or are at risk of developing it. There are several methods available for testing blood sugar, each with its own advantages and applications.

1. Using a Blood Glucose Meter (Glucometer)

A blood glucose meter, or glucometer, is the most common method for self-monitoring blood sugar levels at home. It involves pricking your finger with a lancet to obtain a small blood sample, which is then applied to a test strip inserted into the meter. Severe Hypoglycemia An Emergency Guide For Caregivers And Families

Steps for Using a Glucometer:

Gather Supplies: You'll need a glucometer, test strips, a lancing device (with lancets), and alcohol swabs.
Wash Your Hands: Wash your hands thoroughly with soap and warm water. Dry them well.
Prepare the Lancing Device: Insert a new lancet into the lancing device according to the manufacturer's instructions. Adjust the depth setting as needed for your skin type.
Insert the Test Strip: Insert a test strip into the glucometer. Make sure it is oriented correctly.
Prick Your Finger: Use an alcohol swab to clean the side of your fingertip (usually the side of the ring finger or middle finger). Use the lancing device to prick your finger.
Apply Blood Sample: Gently squeeze your finger to obtain a small drop of blood. Touch the edge of the test strip to the blood droplet. The strip will draw the blood in via capillary action.
Read the Result: The glucometer will display your blood sugar level after a few seconds. Record the result in a logbook or app.
Dispose of Supplies: Safely dispose of the used lancet in a sharps container.

Example:

Imagine Sarah, who has been diagnosed with prediabetes. She decides to monitor her blood sugar levels using a glucometer. After fasting overnight, she follows the steps outlined above and gets a reading of 110 mg/dL. This result indicates that her fasting blood sugar is in the prediabetic range, and she needs to focus on lifestyle changes like diet and exercise to lower her levels.

2. Continuous Glucose Monitoring (CGM)

A continuous glucose monitor (CGM) is a device that continuously tracks your blood sugar levels throughout the day and night. It involves inserting a small sensor under the skin, which measures glucose levels in the interstitial fluid.

How CGM Works:

Insertion: A small sensor is inserted under the skin, usually in the abdomen or arm.
Monitoring: The sensor measures glucose levels in the interstitial fluid every few minutes.
Data Transmission: The CGM device sends the data wirelessly to a receiver or smartphone app.
Real-Time Readings: Users can view their glucose levels in real-time, as well as trends and patterns.
Alerts: CGMs can be programmed to send alerts when glucose levels are too high or too low.

Benefits of CGM:

Continuous Monitoring: Provides a comprehensive picture of blood sugar levels throughout the day.
Trend Identification: Helps identify patterns and trends that might be missed with occasional fingersticks.
Alerts: Warns users of impending high or low glucose levels, allowing for timely intervention.
Improved Management: Facilitates better diabetes management and decision-making regarding diet, exercise, and medication.

Example:

Mark, who has type 1 diabetes, uses a CGM. He notices that his blood sugar levels tend to spike after eating pasta. With this information, he adjusts his insulin dosage and dietary choices to better manage his blood sugar. The CGM also alerts him when his blood sugar drops too low during exercise, allowing him to take quick action by consuming a small snack.

3. A1c Test

The A1c test is a blood test that measures your average blood sugar level over the past 2-3 months. It provides a broader view of your blood sugar control compared to daily blood glucose monitoring. The A1c test is usually performed in a doctor's office or lab.

How the A1c Test Works:

Blood Sample: A healthcare provider takes a blood sample from a vein in your arm or a finger prick.
Laboratory Analysis: The blood sample is sent to a laboratory, where the percentage of hemoglobin that is glycated (attached to glucose) is measured.
Result Interpretation: The A1c result is reported as a percentage. A higher percentage indicates higher average blood sugar levels.

Interpreting A1c Results:

Normal: Below 5.7%
Prediabetes: 5.7% to 6.4%
Diabetes: 6.5% or higher

Example:

Lisa gets her A1c tested during a routine check-up. Her result is 6.0%, which indicates that she has prediabetes. Her doctor advises her to adopt a healthier lifestyle, including a balanced diet, regular exercise, and weight management, to prevent the progression to type 2 diabetes.

Which Method Is Right for You?

The choice of blood sugar monitoring method depends on various factors, including your health condition, lifestyle, and preferences.

Blood Glucose Meter: Suitable for most people who need to monitor their blood sugar levels regularly, especially those with diabetes who require multiple daily readings.
CGM: Ideal for individuals with type 1 diabetes or those with type 2 diabetes who require intensive insulin therapy or struggle with frequent high or low blood sugar levels.
A1c Test: An essential tool for overall diabetes management and assessing the effectiveness of treatment plans over time.

Consulting with your healthcare provider is crucial to determine the best blood sugar monitoring strategy for your specific needs.

What to Do if Your Blood Sugar Is Too High or Too Low

Managing blood sugar levels effectively involves taking appropriate action when they are outside the normal range. Understanding the steps to take for both hyperglycemia (high blood sugar) and hypoglycemia (low blood sugar) is essential for maintaining your health.

Managing High Blood Sugar (Hyperglycemia)

Symptoms of Hyperglycemia:

Frequent urination
Increased thirst
Blurred vision
Fatigue
Headache

Immediate Steps to Take:

Check Your Blood Sugar: Confirm that your blood sugar is indeed high using a glucometer.
Drink Water: Stay hydrated by drinking plenty of water to help dilute excess glucose in your bloodstream.
Take Medication as Prescribed: If you take insulin or oral medications, follow your healthcare provider's instructions. Administer the correct dosage of insulin or take your medication as prescribed.
Exercise (If Appropriate): If your blood sugar is only moderately high (and you don't have ketones in your urine), light exercise can help lower it. However, avoid strenuous exercise if your blood sugar is very high or you have ketones, as this can sometimes raise blood sugar further.
Monitor and Recheck: Monitor your blood sugar levels regularly (every 2-4 hours) and recheck to ensure they are returning to a normal range.

When to Seek Medical Attention:

High Blood Sugar Persists: If your blood sugar remains high despite taking corrective actions.
Ketones Present: If you have type 1 diabetes and ketones are present in your urine, this could indicate diabetic ketoacidosis (DKA), a serious condition requiring immediate medical treatment. Symptoms of DKA include nausea, vomiting, abdominal pain, fruity-smelling breath, and rapid breathing.
Severe Symptoms: If you experience severe symptoms such as confusion, difficulty breathing, or loss of consciousness.

Example Scenario:

John, who has type 2 diabetes, checks his blood sugar after lunch and finds that it is 220 mg/dL. He drinks a large glass of water, takes his prescribed medication, and goes for a brisk walk. He checks his blood sugar again two hours later and finds that it has dropped to 160 mg/dL, which is a more acceptable level.

Managing Low Blood Sugar (Hypoglycemia)

Symptoms of Hypoglycemia:

Shakiness
Sweating
Dizziness
Hunger
Confusion
Irritability
Rapid heartbeat

Immediate Steps to Take:

Check Your Blood Sugar: Verify that your blood sugar is low using a glucometer. Typically, hypoglycemia is defined as a blood sugar level below 70 mg/dL.
Follow the "15-15 Rule": Consume 15 grams of fast-acting carbohydrates.
- Examples:
  - 4 ounces (1/2 cup) of juice or regular soda
  - 1 tablespoon of honey or sugar
  - Glucose tablets (follow the package instructions for 15 grams)
Wait 15 Minutes: Wait 15 minutes and recheck your blood sugar level.
Repeat If Necessary: If your blood sugar is still below 70 mg/dL, repeat the process: eat another 15 grams of fast-acting carbohydrates and wait another 15 minutes.
Eat a Meal or Snack: Once your blood sugar is back to a safe level, eat a meal or snack to prevent another drop. Choose foods that contain both carbohydrates and protein, such as crackers with peanut butter or cheese and whole-grain bread.

When to Seek Medical Attention:

Severe Hypoglycemia: If you become unconscious or unable to treat yourself.
Recurring Episodes: If you experience frequent episodes of hypoglycemia.
No Improvement: If your blood sugar does not improve after following the 15-15 rule several times.

Example Scenario:

Maria, who uses insulin to manage her diabetes, starts to feel shaky and dizzy while at work. She checks her blood sugar and finds that it is 65 mg/dL. She quickly drinks 4 ounces of apple juice, waits 15 minutes, and rechecks her blood sugar. This time, it's 85 mg/dL, so she eats a small granola bar to keep her blood sugar stable.

Preventive Measures

To prevent both hyperglycemia and hypoglycemia, consider the following:

Consistent Meal Timing: Eat meals and snacks at regular times to help stabilize blood sugar levels.
Balanced Diet: Follow a healthy diet that includes a balance of carbohydrates, proteins, and fats.
Regular Exercise: Engage in regular physical activity, but be mindful of how exercise affects your blood sugar.
Medication Management: Take your medications as prescribed and coordinate with your healthcare provider on any adjustments needed.
Blood Sugar Monitoring: Regularly monitor your blood sugar levels to track trends and make informed decisions about your diet, exercise, and medication.
Education: Learn as much as you can about diabetes management and work closely with your healthcare team to develop a personalized plan that fits your needs.

Lifestyle Factors Affecting Blood Sugar Levels

Numerous lifestyle factors can significantly impact your blood sugar levels. Understanding how these factors influence your blood sugar is crucial for effective management and overall health.

1. Diet and Nutrition

Diet plays a pivotal role in managing blood sugar levels. The types of foods you eat and how they are processed can either stabilize or destabilize your glucose levels.

Carbohydrates: Carbohydrates are the primary source of glucose. Choose complex carbohydrates (whole grains, fruits, vegetables) over simple carbohydrates (sugary drinks, processed foods) because they are digested more slowly and cause a gradual rise in blood sugar.
Fiber: High-fiber foods (whole grains, legumes, vegetables) slow down the absorption of sugar and can help improve blood sugar control.
Proteins and Fats: Proteins and healthy fats (nuts, seeds, avocados, olive oil) help stabilize blood sugar levels when consumed with carbohydrates.
Portion Control: Eating appropriate portion sizes is crucial to avoid overconsumption of carbohydrates, which can lead to high blood sugar levels.

Example:

Instead of having a large bowl of white pasta for dinner, choose a smaller portion of whole-wheat pasta with grilled chicken and plenty of vegetables. This balanced meal will provide a steady release of glucose and prevent rapid spikes in blood sugar.

2. Physical Activity and Exercise

Regular physical activity can improve insulin sensitivity and help manage blood sugar levels. Exercise helps your body use glucose more efficiently.

Aerobic Exercise: Activities like walking, jogging, swimming, and cycling can lower blood sugar levels.
Strength Training: Building muscle mass can improve insulin sensitivity and help manage blood sugar over time.
Timing: Be mindful of when you exercise in relation to your meals and insulin injections (if you take insulin). Exercise can lower blood sugar levels, so you may need to adjust your food intake or insulin dosage to prevent hypoglycemia.

Example:

A brisk 30-minute walk after dinner can help lower blood sugar levels and improve insulin sensitivity. Strength training exercises two to three times per week can also contribute to better blood sugar control.

3. Stress Management

Stress can affect blood sugar levels because stress hormones like cortisol and adrenaline can raise glucose levels.

Stress Reduction Techniques:
- Mindfulness Meditation: Regular meditation can help reduce stress and improve overall well-being.
- Deep Breathing Exercises: Practicing deep breathing can calm the nervous system and lower stress hormones.
- Yoga: Yoga combines physical postures, breathing techniques, and meditation to reduce stress and improve relaxation.
- Hobbies and Leisure Activities: Engaging in hobbies and activities you enjoy can help take your mind off stressors and reduce stress levels.

Example:

During a stressful workday, take a few minutes to practice deep breathing exercises or a short meditation session. Over time, incorporating these stress-reducing techniques into your daily routine can help stabilize your blood sugar levels.

4. Sleep

Poor sleep can negatively affect blood sugar control and insulin sensitivity. Aim for 7-9 hours of quality sleep per night.

Sleep Hygiene Practices:
- Consistent Sleep Schedule: Go to bed and wake up at the same time every day, even on weekends.
- Comfortable Sleep Environment: Make sure your bedroom is dark, quiet, and cool.
- Avoid Caffeine and Alcohol: Limit caffeine and alcohol intake, especially in the evening.
- Limit Screen Time: Avoid using electronic devices (phones, tablets, computers) before bed, as the blue light can interfere with sleep.

Example:

Establish a consistent bedtime routine that includes relaxing activities like reading or taking a warm bath. Avoid using your phone or watching TV in bed to improve the quality of your sleep.

5. Alcohol Consumption

Alcohol can have unpredictable effects on blood sugar levels. It can cause both hyperglycemia and hypoglycemia, depending on how much you drink and whether you consume it with food.

Moderation: If you choose to drink alcohol, do so in moderation (up to one drink per day for women and up to two drinks per day for men).
Pair with Food: Always consume alcohol with food to help prevent hypoglycemia.
Monitor Blood Sugar: Check your blood sugar levels before, during, and after drinking alcohol to see how it affects you.

Example:

If you plan to have a glass of wine with dinner, eat a meal that includes protein and complex carbohydrates. Check your blood sugar before and after the meal to see how the alcohol affects your glucose levels.

6. Medications

Certain medications (other than those used to treat diabetes) can affect blood sugar levels.

Corticosteroids: These anti-inflammatory drugs can raise blood sugar levels.
Diuretics: These medications, used to treat high blood pressure, can also raise blood sugar levels.
Antidepressants: Some antidepressants can affect blood sugar levels, either raising or lowering them.

Actionable Advice:

If you take any medications that may affect your blood sugar, talk to your healthcare provider about potential interactions and adjustments you may need to make to your diabetes management plan.
Monitor your blood sugar levels more frequently when starting or changing medications to assess their impact.

7. Hydration

Dehydration can increase blood sugar levels because when you’re dehydrated, your blood becomes more concentrated, which can elevate glucose levels.

Drink Plenty of Water: Aim to drink at least 8 glasses (64 ounces) of water per day.
Monitor Urine Color: Pale yellow urine indicates adequate hydration, while dark yellow urine suggests dehydration.

Example:

Keep a water bottle with you throughout the day and sip on it regularly. Be sure to drink more water during and after exercise, and in hot weather.

8. Smoking

Smoking has been linked to an increased risk of developing type 2 diabetes and can make it harder to control blood sugar levels.

Quit Smoking: Quitting smoking has numerous health benefits, including improving blood sugar control.

Resources:

Talk to your healthcare provider about smoking cessation programs and resources.
Consider using nicotine replacement therapy or other medications to help you quit smoking.

9. Illness

When you’re sick, your body releases stress hormones to fight the illness, which can raise blood sugar levels. Fasting Blood Glucose Your Key To Understanding Diabetes Risk

Monitor Blood Sugar More Frequently: Check your blood sugar more often when you’re sick.
Stay Hydrated: Drink plenty of fluids to prevent dehydration.
Adjust Medication as Needed: Consult with your healthcare provider about adjusting your insulin or medication dosage.
Follow Sick Day Rules: Have a plan for managing your diabetes when you’re sick.

By understanding how these lifestyle factors can influence your blood sugar levels, you can make informed choices and take proactive steps to manage your health effectively. Regular monitoring, along with adjustments to your diet, exercise, and stress management techniques, can help you maintain stable and healthy blood sugar levels.

Conclusion

Maintaining normal blood sugar levels is vital for overall health, and understanding how to test and manage your levels is crucial. By knowing the normal ranges, utilizing appropriate testing methods, and responding effectively to high or low readings, you can take control of your health and prevent long-term complications. Additionally, considering lifestyle factors such as diet, exercise, stress, sleep, and hydration can significantly influence your blood sugar levels and overall well-being. Always consult with your healthcare provider to develop a personalized plan that meets your individual needs. This comprehensive approach ensures you are well-equipped to manage your blood sugar and live a healthier life.