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Confused by mg/dL and mmol/L? A Simple Guide to Blood Sugar Units

04 Sep 2025 by Gregory W. Barsness, M.D.

Confused by mg/dL and mmol/L? A Simple Guide to Blood Sugar Units

Understanding your blood sugar levels is crucial, especially if you have diabetes or are at risk. However, the different units used to measure blood sugar – mg/dL (milligrams per deciliter) and mmol/L (millimoles per liter) – can be confusing. This guide will simplify these units and explain how to convert between them. We’ll cover everything from why different units exist to practical tips for managing your blood glucose readings. Blood Sugar Friendly Meals 21 Easy Recipes For Breakfast Lunch And Dinner

Why Two Different Units?

The two different units arise primarily from geographic preferences and historical convention. mg/dL is predominantly used in the United States, while mmol/L is more common in Europe, Canada, and other parts of the world. Neither unit is inherently "better," but being aware of both is crucial, especially if you travel internationally or encounter lab results using different units. Ultimately, understanding your blood sugar levels in either unit is what matters most.

Understanding mg/dL

mg/dL represents the concentration of glucose in your blood. Specifically, it tells you how many milligrams of glucose are present in each deciliter (100 milliliters) of blood. In the US, most meters and healthcare professionals will use this unit. A typical fasting blood sugar range for a non-diabetic individual is between 70 and 100 mg/dL. Understanding this value helps manage your overall blood sugar levels.

Understanding mmol/L

mmol/L also measures the concentration of glucose, but expresses it in millimoles per liter. One mole is a unit of amount in chemistry, so mmol/L reflects the number of moles of glucose present in each liter of blood. It's widely adopted internationally and you may encounter this unit when using imported devices or consulting with healthcare providers outside the U.S. Keeping track of your blood glucose with these units is equally important.

The Conversion Factor: 18

The magic number to remember when converting between mg/dL and mmol/L is 18. This is the conversion factor that connects the two units.

Converting mg/dL to mmol/L

To convert from mg/dL to mmol/L, divide the mg/dL value by 18.

Formula: mmol/L = mg/dL / 18

Example: If your blood sugar reading is 126 mg/dL, then:

mmol/L = 126 / 18 = 7 mmol/L

Converting mmol/L to mg/dL

To convert from mmol/L to mg/dL, multiply the mmol/L value by 18.

Formula: mg/dL = mmol/L * 18

Example: If your blood sugar reading is 6 mmol/L, then:

mg/dL = 6 * 18 = 108 mg/dL

Quick Reference Table

To make things even easier, here's a quick reference table showing common blood sugar values in both mg/dL and mmol/L. Remember, this provides only a general guideline, and you should always consult with your healthcare provider for personalized targets for blood sugar control.

Blood Sugar Level (Description) mg/dL mmol/L
Normal (Fasting) 70-100 3.9-5.6
Prediabetes (Fasting) 100-125 5.6-6.9
Diabetes (Fasting) 126 or higher 7.0 or higher
Normal (2 hours after eating) Less than 140 Less than 7.8
Diabetes (2 hours after eating) 200 or higher 11.1 or higher

Practical Tips for Managing Your Blood Sugar

Regardless of the units used, effectively managing your blood sugar is key to your health. Here are some practical tips:

  • Regular Monitoring: Check your blood sugar regularly as directed by your healthcare provider. Use a reliable glucometer.
  • Balanced Diet: Focus on a balanced diet rich in fiber, whole grains, fruits, and vegetables. Limit sugary drinks and processed foods. A well-planned diet is fundamental to blood sugar control.
  • Regular Exercise: Engage in regular physical activity, aiming for at least 150 minutes of moderate-intensity exercise per week.
  • Medication Adherence: If you are prescribed medication, take it as directed by your doctor.
  • Stay Hydrated: Drink plenty of water throughout the day.
  • Stress Management: Practice stress-reduction techniques like meditation or yoga, as stress can impact blood sugar levels.
  • Regular Check-ups: See your healthcare provider regularly for check-ups and adjustments to your treatment plan.

Why it Matters: Impact on Health

Maintaining stable blood sugar levels is important for preventing both short-term and long-term complications. Uncontrolled blood sugar can lead to: Fasting Blood Sugar Too High Here Are The Most Common Reasons Why

  • Short-Term: Fatigue, frequent urination, increased thirst, blurred vision.
  • Long-Term: Nerve damage (neuropathy), kidney damage (nephropathy), eye damage (retinopathy), cardiovascular disease.

By understanding your blood sugar units and following your healthcare provider's recommendations, you can significantly reduce your risk of complications and improve your overall quality of life. Effective blood sugar control plays a crucial role in mitigating such risks.

Choosing the Right Meter

When selecting a glucometer, consider the following factors:

  • Ease of Use: Choose a meter that is easy to operate and read, especially if you are new to monitoring your blood sugar.
  • Accuracy: Ensure the meter meets established accuracy standards. Look for certifications and reviews.
  • Cost: Consider the cost of the meter and the test strips. Some meters may be cheaper upfront but have more expensive test strips.
  • Features: Look for features such as memory storage, data download capabilities, and compatibility with continuous glucose monitoring (CGM) systems.
  • Units of Measurement: Verify that the meter displays readings in the unit you prefer (either mg/dL or mmol/L). Some meters allow you to switch between units.

Conclusion

While the distinction between mg/dL and mmol/L might seem confusing at first, understanding the simple conversion factor of 18 makes it easy to navigate these units. The most important thing is to monitor your blood sugar levels regularly, work closely with your healthcare provider, and adopt a healthy lifestyle. With proper management, you can live a long and healthy life, regardless of the units used to measure your blood glucose. A1C Chart Explained Convert Your A1C To Average Blood Sugar Eag

References and Further Reading