mg/dL to mmol/L: Reading Blood Sugar Anywhere

Travelling with a glucose meter, or reading research from another country, means switching between two units that describe the same thing differently.

The two approaches

• mg/dL — milligrams of glucose per decilitre of blood. A mass concentration. Used in the US, Germany, France, Japan and others.
• mmol/L — millimoles per litre. A molar concentration, counting molecules. Used in the UK, Canada, Australia, China and most of Europe.

Converting between mass and molar concentration requires the molar mass of the substance. Glucose is 180.156 g/mol, which gives the factor:

mmol/L = mg/dL ÷ 18.0182 mg/dL = mmol/L × 18.0182

For mental arithmetic, dividing by 18 is accurate to 0.1%.

Reference table

mg/dL	mmol/L	Context
70	3.9	Lower end of normal
90	5.0	Typical fasting
100	5.6	Upper normal fasting
126	7.0	Diabetes diagnostic threshold (fasting)
140	7.8	Upper normal, 2 h after eating
200	11.1	Diabetes diagnostic threshold (random)

Use the mg/dL to mmol/L converter for any value.

General information only — not medical advice. Clinical decisions belong with a healthcare professional.

The factor is glucose-specific

This is the important caveat. 18.0182 comes from glucose's molar mass. Do not reuse it for other analytes. Cholesterol uses 38.67, triglycerides 88.57, creatinine 88.4. Each substance has its own factor because each molecule has a different mass.

HbA1c has its own units too

Long-term control is reported as HbA1c, itself measured two ways: the older DCCT percentage and the newer IFCC value in mmol/mol.

IFCC (mmol/mol) = (DCCT % − 2.15) × 10.929

So 7.0% equals 53 mmol/mol. Different quantity, different conversion — do not confuse it with the daily glucose reading.

Related conversions

• mmol/L to mg/dL
• Molar concentration units