mmo/L to mg/dl Conversion



Because I’m still confused when I see mmo/L BG numbers (used by many people outside the US), I wanted to add a quick reference conversion chart in case anyone else needs to look up what mmo/L (or mg/dl) BG number(s) are being discussed, as I needed too.

From the Joslin Diabetes Center


I detect a trend here on this chart… the mmmo/l is 1/18 of the mg/dL. Which begs the question why on earth are they using a different unit when it’s exactlt the same scale… you’d think the world would standardize on this one.


What’s weird is that both are metric. It’s not like we are sticking to inches and pounds in spite of the rest of the world. We are using metric, but a different metric.

Thanks for posting the conversion @ClaudnDaye. We should make it a sticky on top so we can communicate better with our Canadian friends. :wink:



Awesome idea!


With practice, you may learn to roughly convert in your head. That’s how I do things. Defintely don’t need a calculator anymore to know that 70 is about 4.0 mmol/L and 7 is about 130 mmol/L and 180 is about 10 mmol/L and 250 is about 14 mmol/L. Not exact, but enough that I can get an idea of how high/low people are.

Apparently mmol/L is the standard used in medical journals and for other blood tests, or so I’ve read somewhere. I know that when I get lots of other types of tests (such as cholesterol) they’re also in mmol/L, not whatever units the US uses.


I don’t see mmo/L enough to know it (or even care to learn it). lol. The only number(s) I see here in the US are those on my CGM…which are mg/dl. So it pays for lazy people, like me, to have a quick conversion chart.


Yeah, I learned it from seeing it everywhere. It seems most online diabetes communities are about 90% Americans. So I was going to a calculator every time I read a post, and over time just memorized many of the conversions.


I think the mmo/l system would have been better if we’d all learned that first though… sort of more significant digits in terms of what they mean. EG >10 is high and less than 4 is low is simpler and easier than 70-180 to mean the same exact thing


Also, with mmol/L you can use cool phrases like “in the ones” to mean you were really, really low, or “double digits” to mean you’re high, or “in the teens” to mean you’re getting quite a bit up there…


When I was first diagnosed (in Canada) I used mg/dl for BG measurements. Once I got used to mg/dl for some reason the diabetes clinic I went to changed to mmol/l.

I have no idea if it was just me or if other Canadians went through the same thing.


I was diagnosed in Canada in 1991 and used mmol/L from the start. When were you diagnosed? Maybe the entire country switched over at some point.


We can do the same with mg/dl!

For instance - “in the ones” means you’re nearly dead (or really, really low)…because you’re under 10 mg/dl, in the single digits.

or “in the 3’s, 4’s or 5’s” - way high over 300, 400 or 500.



1987 - I suspect that either the change from mg/dl to mmol/l was a late change in the great Canadian metrication thing or that the first doctor I had post diagnoses was either American or old-school.

@beacher - Did you always use mmol/l?


@Aaron, I believe that it was everyone in Canada. They changed the Canadian standard at some point. I also started out using mg/dl and then we changed to mmol/l.


No. When I started on a pump in 1981, my BG was in the 700s, and I remember a couple of times in the 1980s being told I was in the 500s (with DKA). I had a first-gen Glucometer in 1979 or '80 that measured in mg/dL. I think the main changeover in the health care system started in late 1981, mandated by Metric Commission Canada.


In the other direction (ie - from mmol/L to mg/dl) although often stated as “multiply by 18” you get to the same place but potentially easier mentally to first multiple by 9 then multiply by 2. Benefit being the “9 tables” and the “2 tables” are often times memorized.

Makes it easy for the whole mmol/L numbers.

So the 6 mmol/L can pretty easily be converted mentally as 6 times 9 equals 54 times 2 equals 108. Easier then mentally doing the 6 times 18 directly.


Great tip!


From mg/dl to mmol, my technique is I divide by 10, divide by 2, then add a little bit, about 10%.

It is really fast arithmetic and the result is quite precise (although not perfectly exact).


Since the only time I have to convert is when I’m already on the computer looking at sites like this, I just have an open window for http://www.endmemo.com/medical/unitconvert/Glucose.php.