Blood Sugar mg/dL vs. mmol/L: How to Read Your Test Results Understanding your blood sugar levels is crucial, especially if you have diabetes or are a...

Blood Sugar mg/dL vs. mmol/L: How to Read Your Test Results

Understanding your blood sugar levels is crucial, especially if you have diabetes or are at risk. But things can get confusing quickly because blood sugar, or glucose, can be measured in two different units: mg/dL (milligrams per deciliter) and mmol/L (millimoles per liter). This article breaks down the difference between these units, how to convert between them, and how to interpret your blood sugar test results to maintain optimal health.

What are mg/dL and mmol/L?

Simply put, mg/dL and mmol/L are different ways to express the concentration of glucose in your blood.

mg/dL (milligrams per deciliter): This is the standard unit used in the United States and some other countries. It represents the mass of glucose (in milligrams) present in a specific volume of blood (one deciliter, which is 100 milliliters).
mmol/L (millimoles per liter): This is the unit most commonly used in Canada, Europe, and other parts of the world. It represents the amount of glucose (in millimoles) present in a larger volume of blood (one liter). A mole is a unit of measurement that reflects the number of molecules of a substance.

Why Are There Two Different Units?

The existence of two units is largely due to historical convention and regional preferences in healthcare. While seemingly inconvenient, both units provide the same information about your blood glucose levels – just expressed differently. Understanding both helps you interpret results regardless of where you are in the world or the type of testing equipment used.

Converting Between mg/dL and mmol/L

The conversion between mg/dL and mmol/L is straightforward:

mg/dL to mmol/L: Divide the mg/dL value by 18.
- Example: If your blood sugar is 180 mg/dL, then 180 / 18 = 10 mmol/L.
mmol/L to mg/dL: Multiply the mmol/L value by 18.
- Example: If your blood sugar is 7 mmol/L, then 7 * 18 = 126 mg/dL.

You can also use online blood sugar conversion calculators for quick and accurate results. These calculators are readily available and can be found with a simple web search.

Normal Blood Sugar Ranges

Knowing the normal ranges is essential for understanding your results, regardless of the unit used. These ranges generally apply to adults without diabetes, and it's crucial to consult your doctor to determine your personal target range. These targets may differ based on individual factors like age, pregnancy, or other medical conditions. The values below apply when using a blood glucose meter at home or a lab test.

Time of Day	mg/dL (Normal Range)	mmol/L (Normal Range)
Fasting (after at least 8 hours of no eating)	70-99 mg/dL	3.9-5.5 mmol/L
2 hours after eating	Less than 140 mg/dL	Less than 7.8 mmol/L

Note: Ranges may vary slightly depending on the source. Always consult your doctor.

Understanding Your Blood Sugar Test Results

Now, let's discuss what these numbers mean in the context of common blood sugar tests:

Fasting Blood Sugar (FBS): This measures your blood sugar after an overnight fast (usually 8 hours). It’s a common screening test for diabetes. A fasting blood glucose level between 100 and 125 mg/dL (5.6-6.9 mmol/L) may indicate prediabetes. A level of 126 mg/dL (7.0 mmol/L) or higher on two separate tests typically indicates diabetes.
Oral Glucose Tolerance Test (OGTT): This test measures your blood sugar before and two hours after you drink a sugary liquid. It's often used to diagnose gestational diabetes during pregnancy. A 2-hour blood glucose level of 140-199 mg/dL (7.8-11.0 mmol/L) indicates impaired glucose tolerance (prediabetes), while a level of 200 mg/dL (11.1 mmol/L) or higher indicates diabetes.
A1C Test (Glycated Hemoglobin): This test reflects your average blood sugar levels over the past 2-3 months. It doesn't require fasting and provides a broader picture of your blood sugar control. An A1C level below 5.7% is considered normal. An A1C between 5.7% and 6.4% indicates prediabetes. An A1C of 6.5% or higher indicates diabetes. While the A1C result is presented as a percentage, it reflects the average blood sugar in either mg/dL or mmol/L. Ask your doctor to provide estimated average glucose (eAG) in either unit, to better correlate it to your daily blood glucose readings.
Random Blood Sugar Test: This test measures your blood sugar at any time, regardless of when you last ate. It is used for quick checks, especially if you are experiencing symptoms of high or low blood sugar. A random blood glucose test result of 200 mg/dL (11.1 mmol/L) or higher, along with symptoms of diabetes (frequent urination, excessive thirst, unexplained weight loss), suggests diabetes.

Symptoms of High and Low Blood Sugar

Understanding the symptoms of both hyperglycemia (high blood sugar) and hypoglycemia (low blood sugar) is crucial for managing your health.

Hyperglycemia (High Blood Sugar) Symptoms:

Frequent urination
Increased thirst
Blurred vision
Fatigue
Headaches

Hypoglycemia (Low Blood Sugar) Symptoms:

Shakiness
Sweating
Dizziness
Confusion
Irritability
Rapid heartbeat
Hunger

If you experience any of these symptoms, check your blood glucose levels and consult with your healthcare provider.

Factors That Affect Blood Sugar Levels

Many factors can influence your blood glucose levels, including:

Diet: The types and amounts of food you eat significantly impact your blood sugar. Carbohydrates, in particular, are broken down into glucose.
Physical Activity: Exercise helps lower blood sugar levels by increasing insulin sensitivity and burning glucose for energy.
Stress: Stress hormones can raise blood sugar levels.
Illness: Infections and illnesses can affect blood sugar control.
Medications: Certain medications, like steroids, can increase blood sugar levels. Diabetic medications are specifically aimed at blood glucose control.
Time of Day: Blood sugar levels naturally fluctuate throughout the day.

How to Monitor Your Blood Sugar

Regular blood sugar monitoring is key to managing diabetes and prediabetes. There are several ways to monitor your blood sugar:

Home Blood Glucose Meters: These are portable devices that allow you to check your blood sugar levels at home. You prick your finger with a lancet to obtain a small blood sample, which you then apply to a test strip that the meter reads.
Continuous Glucose Monitors (CGMs): These devices continuously track your blood sugar levels throughout the day and night. A small sensor is inserted under your skin and transmits data to a receiver or smartphone. CGMs can alert you to highs and lows, allowing you to take proactive steps to manage your blood sugar. This allows for better diabetes management.

Tips for Managing Your Blood Sugar

Managing your blood sugar effectively involves a combination of lifestyle changes and, in some cases, medication. Here are some tips:

Follow a Healthy Diet: Focus on whole grains, fruits, vegetables, and lean protein. Limit sugary drinks, processed foods, and refined carbohydrates.
Engage in Regular Physical Activity: Aim for at least 30 minutes of moderate-intensity exercise most days of the week.
Monitor Your Blood Sugar Regularly: Use a home blood glucose meter or CGM as directed by your healthcare provider.
Take Medications as Prescribed: If you have diabetes, take your medications as prescribed by your doctor.
Manage Stress: Practice stress-reduction techniques such as yoga, meditation, or deep breathing exercises.
Get Enough Sleep: Aim for 7-8 hours of quality sleep each night.
Related reading: Decoding Your A1C Chart From Prediabetes Range To A1C Conversion
Work with a Healthcare Team: Regularly consult with your doctor, a registered dietitian, and a certified diabetes educator.

When to See a Doctor

Consult your doctor if:

You have symptoms of diabetes.
Your blood sugar levels are consistently high or low.
You have questions about your blood sugar management plan.
You are experiencing complications of diabetes.

Conclusion

Understanding the difference between mg/dL and mmol/L is fundamental to interpreting your blood sugar test results. By understanding normal ranges, performing conversions when needed, and implementing proactive blood glucose control strategies, you can take control of your health and well-being. Remember to consult with your healthcare provider for personalized advice and management of your blood sugar.