A unit of measure that shows the concentration of a substance in a specific amount of fluid. In most of the world, except for the united states, blood glucose test results are reported as mmol/l. In the united states, milligrammes per deciliter (mg/dl) is used. To convert to mmol/l from mg/dl, divide mg/dl by 18. Example: 180 mg/dl ÷ 18 = 10 mmol/l.