How to Convert mmol/L to mg/dL for Blood Glucose

Close-up of an assortment of blood samples.
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In the United States, blood glucose readings are usually expressed in units of milligrams of glucose per deciliter of blood, or mg/dL. Internationally and in scientific journals, blood glucose is typically expressed in millimoles per liter, or mmol/L. The same way you can convert your weight in kilograms to pounds, you can easily convert your blood glucose values from mmol/L to mg/dL. Both systems are equally precise.

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Doing the Calculation

The easiest way to convert blood glucose from mmol/L to mg/dL is to multiply the value in mmol/L by 18 and change the units. For example, if your reading is 12 mmol/L, you multiply 12 mmol/L by 18, which equals 216, and change the units to mg/dL: 216 mg/dL. The number 18 represents the conversion factor, which relates to the molecular structure and weight of glucose.

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Comparing Blood Glucose Values

When you look at blood glucose values represented in mg/dL, the numbers are much greater than the values expressed in mmol/L. This can lead to confusion, especially if you overlook the units. Knowing a few values in both systems can help you get used to how they compare. For instance, a blood glucose of 100 mg/dL is 5.5mmol/L, 200mg/dL is 11.1 mmol/L and 300 mg/dL is 16.6 mmol/L.

Other Choices in Conversion

Many blood glucose meters allow the user to change the units from mmol/L to mg/dL by changing the settings as described in the instruction booklet. Online calculators can also do the job for you. If Internet access is a problem, you can print out a conversion table and keep it handy.

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