Understanding Your Blood Glucose (BG) Levels: A Complete Chart

17 Sep 2025 By Gregory W. Barsness, M.D.

Understanding Your Blood Glucose (BG) Levels: A Complete Chart

Maintaining healthy blood glucose (BG) levels is crucial for overall well-being, particularly for individuals with diabetes or those at risk of developing the condition. Knowing what constitutes a normal, high, or low BG level can empower you to take proactive steps for managing your health. This comprehensive guide provides a clear understanding of blood glucose levels, complete with charts, explanations, and actionable advice.

Blood glucose, also known as blood sugar, refers to the concentration of glucose in your blood. Glucose is a primary source of energy for the body, derived from the food we eat. The body tightly regulates blood glucose levels through insulin, a hormone produced by the pancreas. Imbalances in blood glucose can lead to various health problems.

Why is monitoring your blood glucose levels so important? Regular monitoring helps you understand how your body responds to different foods, activities, and medications. This knowledge is essential for preventing both hyperglycemia (high blood sugar) and hypoglycemia (low blood sugar), both of which can have serious health consequences.

Key benefits of understanding and monitoring your blood glucose: * Effective diabetes management: Allows for better control over blood sugar levels, reducing the risk of complications. * Early detection of prediabetes: Identifies if blood sugar levels are higher than normal but not high enough to be diagnosed as diabetes, enabling lifestyle changes to prevent progression. * Improved overall health: Helps in making informed decisions about diet, exercise, and medication. * Prevention of emergencies: Reduces the likelihood of severe episodes of hypoglycemia or hyperglycemia that may require hospitalization.

Blood Glucose Level Charts: Target Ranges

Blood glucose levels are measured in milligrams per deciliter (mg/dL) or millimoles per liter (mmol/L). The target ranges vary depending on whether you are testing before a meal (fasting) or after a meal (postprandial). The following charts provide a general guideline, but always consult with your healthcare provider for personalized targets.

1. General Blood Glucose Targets for Adults Without Diabetes:

| Time of Day | Target Range (mg/dL) | Target Range (mmol/L) | | ------------------ | -------------------- | --------------------- | | Fasting (Morning) | 70-99 | 3.9-5.5 | | 2 Hours After Meal | Less than 140 | Less than 7.8 |

2. Blood Glucose Targets for People with Diabetes:

These ranges are generally recommended but can vary based on individual needs and circumstances. Always consult with your healthcare provider.

| Time of Day | Target Range (mg/dL) | Target Range (mmol/L) | | ------------------ | -------------------- | --------------------- | | Fasting (Morning) | 80-130 | 4.4-7.2 | | 2 Hours After Meal | Less than 180 | Less than 10.0 |

3. Blood Glucose Levels Indicating Prediabetes:

| Time of Day | Range (mg/dL) | Range (mmol/L) | | ------------------ | ------------- | -------------- | | Fasting (Morning) | 100-125 | 5.6-6.9 | | 2 Hours After Meal | 140-199 | 7.8-11.0 | What Are Normal Blood Sugar Levels A Complete Chart By Age

4. Blood Glucose Levels Indicating Diabetes:

| Time of Day | Range (mg/dL) | Range (mmol/L) | | ------------------ | ------------- | -------------- | | Fasting (Morning) | 126 or higher | 7.0 or higher | | 2 Hours After Meal | 200 or higher | 11.1 or higher | | Random | 200 or higher | 11.1 or higher |

Key Considerations for Blood Glucose Targets: * Age: Older adults may have different targets. * Health conditions: Existing conditions like heart disease can influence targets. * Medications: Certain medications can affect blood glucose levels. * Lifestyle: Diet and physical activity play significant roles. * Pregnancy: Pregnant women with diabetes have stricter targets.

Understanding Hyperglycemia and Hypoglycemia

Hyperglycemia occurs when blood glucose levels are too high, typically above 180 mg/dL two hours after eating or above 130 mg/dL fasting. Hypoglycemia, on the other hand, is when blood glucose levels are too low, generally below 70 mg/dL.

Hyperglycemia: High Blood Sugar

Causes of Hyperglycemia: * Dietary indiscretions: Eating too many carbohydrates or sugary foods. * Insufficient insulin: Not taking enough insulin or oral diabetes medication. * Illness: Infections or other illnesses can increase blood sugar levels. * Stress: Emotional stress can affect blood sugar control. * Inactivity: Lack of physical activity. * Certain medications: Steroids and some other medications can raise blood glucose.

Symptoms of Hyperglycemia: * Frequent urination * Increased thirst * Blurred vision * Fatigue * Headache

Management of Hyperglycemia: 1. Check blood sugar levels: Monitor frequently. 2. Adjust medication: Follow your healthcare provider's instructions. 3. Stay hydrated: Drink plenty of water. 4. Engage in light exercise: If appropriate, to help lower blood sugar. 5. Consult your doctor: If levels remain high despite adjustments.

Left untreated, hyperglycemia can lead to serious complications, including: * Diabetic Ketoacidosis (DKA): A life-threatening condition caused by a buildup of ketones in the blood. * Hyperosmolar Hyperglycemic State (HHS): A severe condition with extremely high blood sugar levels and dehydration. * Long-term complications: Such as nerve damage, kidney damage, and cardiovascular problems. What Is Severe Hypoglycemia A Safety Guide For Persons With Diabetes

Hypoglycemia: Low Blood Sugar

Causes of Hypoglycemia: * Excess insulin: Taking too much insulin or oral diabetes medication. * Skipping meals: Not eating enough food, especially carbohydrates. * Excessive exercise: Engaging in strenuous physical activity without adequate carbohydrate intake. * Alcohol consumption: Especially without food. * Certain medical conditions: Kidney or liver problems.

Symptoms of Hypoglycemia: * Shakiness * Sweating * Dizziness * Confusion * Hunger * Irritability * Rapid heartbeat * Blurred vision * Seizures (in severe cases) * Loss of consciousness (in severe cases)

Management of Hypoglycemia: 1. Check blood sugar levels: Confirm hypoglycemia. 2. Follow the 15-15 rule: Consume 15 grams of fast-acting carbohydrates (e.g., glucose tablets, fruit juice, or regular soda) and recheck blood sugar in 15 minutes. 3. Repeat if necessary: If blood sugar is still below 70 mg/dL, repeat the 15-15 rule. 4. Eat a meal or snack: Once blood sugar is above 70 mg/dL, eat a meal or snack to stabilize levels. 5. Seek medical attention: If symptoms persist or worsen.

Examples of 15 grams of fast-acting carbohydrates: * 4 glucose tablets * 1/2 cup (4 ounces) of fruit juice * 1/2 can (6 ounces) of regular soda * 1 tablespoon of honey or sugar

Note: Avoid foods high in fat or protein, as they can slow down the absorption of glucose.

Left untreated, severe hypoglycemia can lead to: * Seizures * Loss of consciousness * Brain damage * Death

Factors Affecting Blood Glucose Levels

Numerous factors can influence your blood glucose levels. Being aware of these can help you make informed decisions about your lifestyle and manage your health more effectively.

1. Diet: * Carbohydrates: The type and amount of carbohydrates you consume have a direct impact on blood glucose levels. Simple sugars can cause a rapid spike, while complex carbohydrates are digested more slowly. * Fiber: High-fiber foods can help slow down the absorption of sugar and improve blood sugar control. * Protein and Fat: These nutrients can also affect blood sugar levels, particularly when consumed in large amounts.

2. Physical Activity: * Exercise: Physical activity can help lower blood sugar levels by increasing insulin sensitivity and utilizing glucose for energy. * Timing: The timing of exercise in relation to meals and insulin injections can impact blood sugar levels. * Type: Both aerobic and resistance exercises can improve blood sugar control.

3. Medications: * Insulin: Different types of insulin (e.g., rapid-acting, short-acting, intermediate-acting, and long-acting) have varying effects on blood sugar levels. * Oral Diabetes Medications: Medications like metformin, sulfonylureas, and others work through different mechanisms to lower blood sugar. * Other Medications: Some non-diabetes medications, such as steroids, can also affect blood glucose levels.

4. Stress: * Hormones: Stress hormones, such as cortisol and adrenaline, can raise blood sugar levels. * Management: Finding healthy ways to manage stress, such as exercise, meditation, or counseling, can help improve blood sugar control. The Critical Link Between Blood Sugar Insulin And Your Health

5. Illness: * Infections: Infections can increase blood sugar levels due to the release of stress hormones. * Monitoring: Monitoring blood sugar more frequently during illness is essential.

6. Alcohol: * Effects: Alcohol can initially lower blood sugar levels but may cause a rebound effect later. * Moderation: Consume alcohol in moderation and always with food.

7. Hydration: * Dehydration: Dehydration can concentrate blood glucose, leading to higher readings. * Water Intake: Staying adequately hydrated is essential for maintaining healthy blood sugar levels.

8. Sleep: * Lack of Sleep: Insufficient sleep can affect hormone levels and insulin sensitivity, leading to increased blood sugar. * Routine: Establishing a regular sleep routine can help improve blood sugar control.

9. Menstrual Cycle: * Hormonal Changes: Hormonal fluctuations during the menstrual cycle can affect blood sugar levels. * Tracking: Monitoring blood sugar closely during this time can help manage any fluctuations.

10. Time of Day: * Dawn Phenomenon: A natural rise in blood sugar levels in the early morning hours due to hormonal changes. * Monitoring: Being aware of this phenomenon can help in adjusting medication or meal timings.

Monitoring Your Blood Glucose Levels

Regular monitoring of blood glucose levels is a cornerstone of diabetes management. The frequency and timing of monitoring will depend on your individual needs and treatment plan.

Methods of Monitoring:

Blood Glucose Meter (Glucometer):
- Procedure: A small blood sample, typically obtained from a finger prick, is placed on a test strip, which is then inserted into the meter for a reading.
- Frequency: Varies depending on the type of diabetes, treatment plan, and individual circumstances. Some individuals may need to test multiple times a day, while others may only need to test occasionally.
- Accuracy: Ensure the meter is properly calibrated and the test strips are not expired for accurate readings.
Continuous Glucose Monitoring (CGM):
- Procedure: A small sensor is inserted under the skin and measures glucose levels in the interstitial fluid continuously throughout the day and night. The sensor transmits data to a receiver or smartphone.
- Benefits: Provides real-time glucose readings, trends, and alerts for high and low blood sugar levels.
- Suitability: Ideal for individuals who require frequent monitoring or have difficulty detecting hypoglycemia.
Hemoglobin A1c (HbA1c) Test:
- Procedure: A blood test that measures average blood sugar levels over the past 2-3 months.
- Frequency: Typically performed every 3-6 months, as recommended by your healthcare provider.
- Target: The target HbA1c level is usually below 7% for most individuals with diabetes.

Tips for Accurate Blood Glucose Monitoring:

Wash your hands: Thoroughly wash your hands before testing to avoid contamination.
Use the correct test strips: Ensure you are using the test strips recommended for your meter.
Check expiration dates: Do not use expired test strips.
Calibrate your meter: Calibrate your meter regularly, as recommended by the manufacturer.
Record your results: Keep a log of your blood sugar readings to track trends and patterns.
Consult your healthcare provider: Discuss your monitoring results with your healthcare provider and make any necessary adjustments to your treatment plan.

When to Check Your Blood Glucose Levels:

Fasting (before breakfast): Provides a baseline reading.
Before meals: Helps determine the appropriate insulin dose or medication dosage.
2 hours after meals: Indicates how your body is responding to the food you have eaten.
Before bedtime: Ensures your blood sugar levels are stable overnight.
Before, during, and after exercise: Helps prevent hypoglycemia or hyperglycemia during physical activity.
When you suspect hypoglycemia or hyperglycemia: If you experience symptoms.
During illness: Monitor more frequently to manage blood sugar fluctuations.

Lifestyle Changes to Help Manage Blood Glucose Levels

Lifestyle modifications are integral to managing blood glucose levels effectively, particularly for individuals with prediabetes or diabetes.

1. Dietary Modifications:

Choose complex carbohydrates: Opt for whole grains, fruits, vegetables, and legumes over refined carbohydrates and sugary foods.
Limit processed foods: Reduce your intake of processed foods, which are often high in sugar, unhealthy fats, and sodium.
Increase fiber intake: Include plenty of fiber-rich foods in your diet to slow down the absorption of sugar and improve blood sugar control.
Control portion sizes: Practice portion control to prevent overeating and maintain a healthy weight.
Stay hydrated: Drink plenty of water throughout the day to help regulate blood sugar levels.
Consult a dietitian: Work with a registered dietitian or certified diabetes educator to develop a personalized meal plan.

2. Regular Physical Activity:

Aerobic exercise: Engage in moderate-intensity aerobic exercise, such as brisk walking, cycling, or swimming, for at least 150 minutes per week.
Resistance training: Incorporate resistance training exercises, such as weight lifting or bodyweight exercises, at least two days per week.
Consistency: Aim for consistency in your exercise routine to maintain stable blood sugar levels.
Monitor blood sugar: Check your blood sugar before, during, and after exercise to prevent hypoglycemia.
Consult your doctor: Discuss your exercise plans with your healthcare provider before starting a new routine.

3. Stress Management:

Identify stressors: Recognize the sources of stress in your life and develop strategies for managing them.
Practice relaxation techniques: Engage in relaxation techniques, such as deep breathing, meditation, or yoga, to reduce stress.
Get adequate sleep: Prioritize getting enough sleep to support overall health and reduce stress levels.
Seek support: Connect with friends, family, or a therapist for support and guidance.

4. Weight Management:

Achieve and maintain a healthy weight: Losing even a small amount of weight can improve insulin sensitivity and blood sugar control.
Calorie balance: Consume fewer calories than you burn to create a calorie deficit for weight loss.
Balanced diet: Follow a balanced diet that is rich in nutrients and low in processed foods.
Regular exercise: Engage in regular physical activity to burn calories and build muscle.

5. Smoking Cessation:

Negative impact: Smoking can worsen insulin resistance and increase the risk of diabetes complications.
Seek help: If you smoke, seek help from your healthcare provider or a smoking cessation program.

6. Alcohol Consumption:

Moderation: Consume alcohol in moderation, if at all, and always with food.
Effects: Alcohol can initially lower blood sugar levels but may cause a rebound effect later.
Monitor blood sugar: Check your blood sugar levels after consuming alcohol.

Conclusion

Understanding your blood glucose levels is vital for maintaining optimal health, especially if you have diabetes or are at risk. By using the charts and information provided in this comprehensive guide, you can gain valuable insights into what constitutes a normal, high, or low blood sugar level. Remember to monitor your levels regularly, make informed lifestyle choices, and consult with your healthcare provider for personalized guidance. Empower yourself with knowledge and take proactive steps toward better health and well-being.