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Blood Glucose Levels Explained: A Full Chart for mg/dL and mmol/L

04 Sep 2025 by Simon J. Laplante, M.D.

Blood Glucose Levels Explained: A Full Chart for mg/dL and mmol/L

Understanding your blood glucose levels is critical for maintaining good health, especially if you have diabetes or are at risk. This comprehensive guide will break down everything you need to know about blood sugar, providing a detailed chart for both mg/dL and mmol/L measurements, explaining what the numbers mean, and outlining steps you can take to maintain healthy levels. We'll cover normal ranges, prediabetes, diabetes, and what to do if your blood sugar is too high or too low. Normal Blood Sugar Levels By Age A Chart For Adults And Seniors

Why Monitoring Blood Glucose Is Important

Regular blood glucose monitoring helps you and your healthcare provider:

  • Track the effectiveness of your diabetes management plan.
  • Understand how diet and exercise affect your blood sugar levels.
  • Recognize and address potential problems, such as hyperglycemia (high blood sugar) or hypoglycemia (low blood sugar).
  • Make informed decisions about medication, food, and activity.

Understanding Blood Glucose Measurements: mg/dL vs. mmol/L

Blood glucose levels are typically measured in two units:

  • mg/dL (milligrams per deciliter): This is the standard unit used in the United States.
  • mmol/L (millimoles per liter): This is the unit used in most other parts of the world.

It's essential to know which unit your meter uses and understand the corresponding values. To convert from mg/dL to mmol/L, divide by 18. To convert from mmol/L to mg/dL, multiply by 18.

Blood Glucose Level Chart: A Comprehensive Guide

This chart provides a detailed overview of blood glucose levels at various times of the day and their corresponding categories. Note that these are general guidelines and individual targets may vary based on specific health conditions and doctor's recommendations.

Category Fasting Blood Sugar (mg/dL) Fasting Blood Sugar (mmol/L) 2 Hours After Meal (mg/dL) 2 Hours After Meal (mmol/L)
Normal Less than 100 mg/dL Less than 5.6 mmol/L Less than 140 mg/dL Less than 7.8 mmol/L
Prediabetes 100 to 125 mg/dL 5.6 to 6.9 mmol/L 140 to 199 mg/dL 7.8 to 11.0 mmol/L
Diabetes 126 mg/dL or higher 7.0 mmol/L or higher 200 mg/dL or higher 11.1 mmol/L or higher

Note: Consult with your healthcare provider for personalized targets.

Blood Glucose Levels: Understanding the Ranges

Normal Blood Sugar Levels

Normal blood sugar levels indicate that your body is efficiently processing glucose. Fasting blood sugar should be below 100 mg/dL (5.6 mmol/L), and blood sugar two hours after a meal should be below 140 mg/dL (7.8 mmol/L). Maintaining these levels is crucial for overall health and preventing long-term complications.

Prediabetes Blood Sugar Levels

Prediabetes means your blood sugar levels are higher than normal but not high enough to be diagnosed as diabetes. This condition increases your risk of developing type 2 diabetes, heart disease, and stroke. Fasting blood sugar in the prediabetic range is 100 to 125 mg/dL (5.6 to 6.9 mmol/L), and two hours after a meal, it's 140 to 199 mg/dL (7.8 to 11.0 mmol/L). Lifestyle changes, such as diet and exercise, can often help reverse prediabetes.

Diabetes Blood Sugar Levels

Diabetes is diagnosed when fasting blood sugar is 126 mg/dL (7.0 mmol/L) or higher on two separate tests, or when blood sugar two hours after a meal is 200 mg/dL (11.1 mmol/L) or higher. Proper management through medication, diet, and exercise is essential for preventing complications. 7 Day Blood Sugar Diet Plan Delicious Meals To Stabilize Your Levels

What to Do If Your Blood Sugar Is Too High (Hyperglycemia)

Hyperglycemia, or high blood sugar, can occur for various reasons, including:

  • Eating too many carbohydrates
  • Missing a dose of diabetes medication
  • Illness or stress
  • Inactivity

Symptoms of hyperglycemia include:

  • Increased thirst
  • Frequent urination
  • Blurred vision
  • Fatigue
  • Headache

If your blood sugar is consistently high, consult your healthcare provider. They may adjust your medication or provide guidance on diet and lifestyle changes. Also, drink plenty of water to help flush out excess glucose.

What to Do If Your Blood Sugar Is Too Low (Hypoglycemia)

Hypoglycemia, or low blood sugar, can happen when:

  • You take too much insulin or other diabetes medication
  • You skip meals
  • You exercise intensely without eating enough

Symptoms of hypoglycemia include:

  • Shakiness
  • Sweating
  • Dizziness
  • Confusion
  • Rapid heartbeat
  • Irritability

If you experience hypoglycemia, follow the "15-15 rule": Eat 15 grams of fast-acting carbohydrates (like glucose tablets or juice), wait 15 minutes, and check your blood sugar again. Repeat until your blood sugar is back within the normal range. Carry a source of fast-acting carbs with you at all times.

Tips for Maintaining Healthy Blood Sugar Levels

  • Follow a balanced diet: Focus on whole foods, including fruits, vegetables, lean proteins, and whole grains. Limit sugary drinks and processed foods. A healthy diet is foundational.
  • Engage in regular physical activity: Aim for at least 30 minutes of moderate-intensity exercise most days of the week. Regular exercise improves insulin sensitivity.
  • Monitor your blood sugar regularly: Use a blood glucose meter or continuous glucose monitor (CGM) to track your levels and identify patterns. Consistent monitoring empowers informed decisions.
  • Take medications as prescribed: Adhere to your doctor's instructions for diabetes medication.
  • Manage stress: Practice stress-reducing techniques like meditation, yoga, or deep breathing exercises.
  • Get enough sleep: Aim for 7-8 hours of quality sleep each night.
  • Stay hydrated: Drink plenty of water throughout the day.

Conclusion: Taking Control of Your Blood Glucose

Understanding and managing your blood glucose levels is essential for preventing complications and maintaining a healthy lifestyle. By using the information and chart provided in this guide, you can take proactive steps to monitor your blood sugar, make informed decisions about your diet and exercise, and work closely with your healthcare provider to achieve your target range. Remember, individual needs may vary, so always consult with your doctor for personalized recommendations. By staying informed and taking consistent action, you can live a healthier, more vibrant life. What Is Impaired Fasting Glucose And What Does It Mean For Your Future Health

References and Further Reading