How to convert mg / dL to mmol / L?

How to convert mg / dL to mmol / L?

mg/dL=0.001g/0.001L=g/L
If we know the relative molecular mass m of the substance, then the mass of the substance is equal to the mass divided by the relative molecular mass. So g / l can be converted into (g / M) / L, that is, mol / L, and then multiplying the molecule by 1000 can be converted into mmol / L