Converting: From Mg/dL to Mmol/L
Units of Measurement used in
blood-tests differ between the U.S.
and other countries
How to compare and convert
In the United States, units of measurement used in blood tests differ from units of measurement used in the rest of the world.
The U.S. uses milligrams per deciliter (mg/dL) whereas Canada, Great Britain, and most of the other countries use millimoles per litre (mmol/L).
The values expressed by one type of unit can be converted to the other by using a multiplication or division factor, as described below. This is very useful when a publication from the U.S. is being read elsewhere in the world, or when, in the U.S., there are references in material from Canada, Australia, the U.K. or other countries.
Glucose, cholesterol, and triglycerides
Of especial interest in blood test results are those for blood glucose, cholesterol, and triglycerides.
To convert from mg/dL to mmol/L
- For Blood glucose ……… divide by 18
- For Cholesterol ……….. divide by 39
- For Triglycerides ……… divide by 89
To convert from mmol/L to mg/dL
- For Blood glucose ……… multiply by 18
- For Cholesterol ……….. multiply by 39
- For Triglycerides ……… multiply 89
To illustrate:
A blood glucose meter reading in the U.S. of 120 (in mg/dl) is the same as 6.7 mmol/l (120 / 18 = 6.7).
And a blood glucose meter reading of 6.5 (in mmol/l) is the same as 117 mg/dl (6.5 x 18 = 117 mg/dl).
Note: In case anyone wonders why the mutiplication – division factor is not the same for each of the three different substances, it is because the mg/dL and the mmol/L, are units that relate to different physical properties, one, the mg, is a measure of weight while the mmol is a specific quantity of a substance.
A milligram of one substance obviously has the same weight as a milligram of any other substance. But equal quantities of different substances will have different weights depending on their composition.
For example, consider an exact quantity of each of glucose, cholesterol, and triglyceride, say for instance, a single spoonful of each. While their quantities of a single spoonful are the same, the individual weights of each of those spoonfuls will be different.
So it can be stated as:
The milligram (mg) is a unit of mass (weight for practical purposes).
The millimol (mmol) is a unit defining a quantity of a substance.
Mole and millimole
A millimole is one-thousandth of the quantity called a mole. The Mole is a precise physical quantity and is often used by chemical engineers to refer to chemical substances. The quantity term millimol can be confusing when used in reference to blood test measurements where milligram-weight amounts might be easier to relate to.
A change in measurement units?
There are currently discussions among health organizations to produce a formula that can convert and report the blood test results such as the A1C, in mg/dL instead of using the mmol/L, thus making it somewhat easier to comprehend.
A simple explanation of blood tests for diabetes can be found here
The A1C blood test results are given as percentages
The A1C Blood test is usually taken about every three months and is an important test because it provides an indication of a patient’s blood glucose levels over the prior three month period. That makes it a better indicator of diabetes control over that timespan compared to the fasting blood sugar measurement that represents only a brief prior period measured in hours.
The test is also referred to by several other names: HbA1c, glycosolated hemoglobin or glycated hemoglobin, etc, names derived from the molecular components of the blood cells that are measured by the test and which include the circulating glucose remaining in the bloodstream.
The A1C results are given as a percentage of the blood cells in the test sample that have glucose attached to them. Non diabetics normally have an A1C percentage of less than 6%. Although there is not total agreement within the medical community, generally the A1C target result looked for in the case of the diabetic patient is that it should be less than 7%.
Better still would be 6.5% and down to as near 6% as can be achieved. The higher the percentage the higher is the risk of diabetic complications developing and such complications might occur over a shorter period of time.
Also to monitor – Blood Pressure
Target maximum for diabetic persons is quoted as “130 systolic over 80 diastolic” Those units are in millimeters of mercury. For non diabetics the target maximum is 140 over 80. Those are maximums, lower is better, a systolic of 120 would be good.
A person’s maximum blood pressures is generated by the beating heart followed by a drop in pressure between heart beats.
The blood pressure while the heart is beating is called the Diastolic blood pressure.
The blood pressure between heart beats while the heart is relaxed is called the Sysytolic blood pressure.
Blood pressure levels are determined by measuring the amount of mercury in millimeters (mmHg) that can be moved in a measuring device, usually a sphygmomanometer, that is attached around the patient’s arm.
Units for Weight Measurement also differ in some other countries
It is often necessary to monitor weight, especially for the diabetic person.
In the United States and Canada weight is measured in pounds.
In some countries the measurement of body weight is in kilograms, and in some English speaking countries such as the U.K. the older Imperial system weight called the Stone, which is 14 lbs, is used. In this system a person would weigh a multiple of several stone plus a part of a stone in pounds. For example a person weighing 175 pounds would be 12 stone 7 pounds. Sometimes, old methods are hard to replace.
If you wish to convert pounds to kilograms go here.
For More about Body Weight go here and about the Body Mass Index go here.
