Blood Glucose Converter

Blood glucose: mg/dL and mmol/L conversion

Conversion uses the molar mass of glucose (≈ 180 g/mol): mmol/L = mg/dL / 18 and mg/dL = mmol/L · 18. Example: 100 mg/dL = 100 / 18 ≈ 5.55 mmol/L. The international SI standard is mmol/L (UK, most of Europe, Canada use both); Brazil and the US mostly use mg/dL. Fasting ranges: normal 70-99 mg/dL (3.9-5.5 mmol/L); pre-diabetes 100-125 mg/dL (5.6-6.9 mmol/L); diabetes ≥ 126 mg/dL (≥ 7.0 mmol/L). HbA1c (glycated hemoglobin) reflects average glucose over ~3 months: normal < 5.7%, pre-diabetes 5.7-6.4%, diabetes ≥ 6.5%.

Applications: meters, CGM and international records

Used to read capillary glucose meters set to a different unit than your country's standard, with CGM systems (Freestyle Libre, Dexcom) that may default to mmol/L, in international medical records when patients travel, in insulin bolus dosing (carb ratio and correction factor depend on the unit), and in gestational diabetes monitoring where targets are tight and unit confusion is risky.

FAQ

Why is the factor 18? Glucose has a molar mass of ~180.16 g/mol. Converting mg/dL (mg per 100 mL) into mmol/L requires dividing by 18.0182 ≈ 18.

Can I switch units on my meter? Most modern meters have a settings option. Some are locked to a single unit at the factory — check the manual.

Does HbA1c convert with the same factor? No. HbA1c uses its own formulas (NGSP % ↔ IFCC mmol/mol). It is not a direct conversion of mg/dL.

Are the diagnostic cutoffs the same worldwide? Yes — ADA, WHO and SBD use the same numerical thresholds, only expressed in different units.