Actually it is mmol/L not mmo/L. Just sayin 
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Thanks! I’ve changed the title. I’m quite surprised that I never spotted that typo.
There are too many bloody L’s in it, and the / looks a bit like a lower case L too. Easy to scan and miss!
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I much prefer mM. Quite apart from the fact that I learned to spell litre with a lowercase ell when I was young (I would probably have failed if I said “L”) and quite apart from the fact that the use of multiple letters (“mol”) in a quantity that can be qualified (“mmol”) is pernicious (like, is it mmol, m-mol, mm-ol, or mmo-l?) M is the right letter.
All is right in the world if you just remember Avogadro’s number and the molecular weight of sugar. 6.22 x 10 to the 23rd power, and 342.3 grams per mole. Then all these conversions make perfect sense. Convert to your hearts content and figure out exactly how many molecules of sugar one unit of insulin covers.
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Avogadro’s number factors out; that’s why it works to say “5mmol/L” - “mol” is just Avogadro’s number. I was certainly taught it around 1976 as part of high school chemistry, well, I was taught 6.023E23 but found a better approximation 6.022169E23+/-.00014E23 and I’ve remembered it since then. However I don’t think I have ever had to use it in a computation; this is why it just appears as “mol” in equations.
As a result the convertion factor just comes from the molecular weight of glucose. It is necessary to get it right of course, but a chemist will know the formula (C6H12O6 - six carbo “C” hydrate “H20” units) and remember the atomic weights (C-12g/mol, H - 1, O - 16) to get the molecular weight - 180g/mol). More likely these days just look it up on Google; 180.156g/mol.
Then the convertion factor from “thousandths of a mole of glucose per litre of blood” to “thousandths of a gramme of glucose per tenth of a litre of blood” is just:
blood glucose in mM: bg mmol/L
(milli)grammes glucose per litre: 180.156*bg mg/L (See how the ‘mol’ disappears.)
milligrammes glucose per tenth of a litre: 18.0156*bg mg/dL
I.e. the convertion factor is just the molecular weight of glucose divided by 10, which is kind of easy.
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As always, FUD has the best reference material.
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In SI units, unit abbreviations only have an initial upper case if they are named after a real person. Hence A for amperes, V for volts, m for metres, N for newton, K for kelvin, s for second. Ampere, Volta, Newton and Kelvin were people. There was no Mr Metre or Ms Second.
Mole was not a person, so it cannot be M and m is already taken. If you want to change the SI system, it’ll take more than a post here
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Actually someone is going to point out that the abbreviation for litre is L. Oh well.
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Despite the reference I gave?
Note that I was referring to the whole unit “mol/L” - “M” is the unit symbol for “molar”, a measure of the concentration of a substance expressed as a molarity; the number of moles in a litre of water. I admit, when I was 16 and learnt all this I did have a set of peculiar images form in my mind which tended to disrupt my ability to pay attention in the classroom so I may have missed something.
Technically neither the use of molar for concentrations nor the use of litre for volumes are SI units but in fact chemists have been using them since the adoption of the SI. So they don’t obey the rules 
. “mol” is an SI ‘unit’ (it is, in fact, just a count, so ‘unit’ is a bit misleading). The SI unit of volume is the cubic metre, so the unit of concentration is mol/m^3, which, ironically, is actually the unit we are using for blood glucose; 1mol/m^3 is 1mmol/L!
Your memory of High School Chemistry is clearly better than mine LOL.
By the way, looking at your profile, very similar history. Me: juvenile onset at 13 (1975). Drinker. You’re clearly lighter and fitter though
Sam, you are correct about the 1/18 ratio. That ratio follows from the fact that the molar mass of glucose is 180.156g/mol. That, and a touch of stoichiometry. 
BTW, I’m new here. I was diagnosed on New Years Eve after 6 harrowing hours in the ER.
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Wow… I should have read the whole thread… Oops.
Don’t feel bad @Mike2.718281828, we are a goofy and pretty scientific lot so high brow humor is always appreciated, if not always understood 
Looking forward to your contributions.
Thanks, Chris. The forum is full of informative discussion.
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This is awesome! Thanks for sharing.
The litre, along with metric ton, degree, hectare and a few others, is not an official SI unit but is widely used enough to be accepted within the system, so it doesn’t have to follow the rules. By convention, capital L is used to prevent confusion with the numeral 1 or, in many fonts, uppercase I (eye) or lowercase l (ell). (See what I mean?) Capital L is universal in Canada, but in Europe the lowercase is common; on food packaging it’s often a script (ℓ) so it’s easily distinguished.
Yours sincerely,
Mr. Trivia
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And, of course, us darn Americans will insist it is Liter instead of Litre…
If you wish. As an American I don’t want to make life difficult for myself, therefore this publication:
is in my round filing cabinet.
Somewhere, way back, there is a set of rules in the Federal Register which covers the variant spellings adopted in the US post-Webster. It basically tells Webster what he should do with his whatever. I can’t find the right link, however I did find this from 1977:
Pretty much we are retrograde; we’re just making ourselves different from the rest of the world out of arrogance, I guess.