Which unit is the SI unit for fasting glucose expression?

Which unit is the SI unit for fasting glucose expression?

• A. mg/dL
• B. mg/mL
• C. mmol/L
• D. μmol/L

Answer: (C)

Glucose concentration is described using a molar concentration, which counts how many molecules are present per unit of volume. In clinical practice, the standard unit for this is millimoles per liter, because it directly reflects the amount of substance in the fluid and keeps numbers in a convenient range for physiological values. For fasting glucose, typical values fall around 4 to 6 mmol/L. For example, 90 mg/dL translates to about 0.90 g/L. Dividing by glucose’s molar mass (roughly 180 g/mol) gives ≈0.005 mol/L, which is 5 mmol/L. This illustrates how a mass per volume (mg/dL) can be converted to a molar concentration (mmol/L) for standard reporting. Other units like mg/dL express mass per volume and are not SI-based, and while μmol/L is technically a valid SI-derived unit, it yields much smaller numbers (and is less practical for the common physiological range of glucose). Using mmol/L aligns with the mole-per-liter concept and keeps clinical values clean and comparable across labs.

Glucose concentration is described using a molar concentration, which counts how many molecules are present per unit of volume. In clinical practice, the standard unit for this is millimoles per liter, because it directly reflects the amount of substance in the fluid and keeps numbers in a convenient range for physiological values.

For fasting glucose, typical values fall around 4 to 6 mmol/L. For example, 90 mg/dL translates to about 0.90 g/L. Dividing by glucose’s molar mass (roughly 180 g/mol) gives ≈0.005 mol/L, which is 5 mmol/L. This illustrates how a mass per volume (mg/dL) can be converted to a molar concentration (mmol/L) for standard reporting.

Other units like mg/dL express mass per volume and are not SI-based, and while μmol/L is technically a valid SI-derived unit, it yields much smaller numbers (and is less practical for the common physiological range of glucose). Using mmol/L aligns with the mole-per-liter concept and keeps clinical values clean and comparable across labs.