One has to kind of assume this is shorthand for 'the dosage of insulin as recorded by the patient in their treatment diary" — I keep one of these, and it is referred to as my 'carnet'.

--------------------------------------------------
Note added at 12 hrs (2022-12-01 07:22:00 GMT)
--------------------------------------------------

I've never personally seen the version written in full like that, but I'm sure it is probably correct — though do note it isn't necessarily only the glycémie that is noted, but, for example, like mine, the insulin taken and possibly other stats as well.
However, what I think it most important is not to leave out the 'subject' (or as I've suggested rendering it, 'patient'), because this is specifically a continuous daily record kept by the patient — as such, it is more frequent than the objective tests but the patient may make mistakes or even lie! Hence the qualifier, in essence, that it needs to be taken with a pinch of salt!

--------------------------------------------------
Note added at 12 hrs (2022-12-01 07:23:44 GMT)
--------------------------------------------------

Non-native speakers of EN often have trouble deciphering telegraphic expressions like this, where it takes a very fine knowledge of the language and also context to untangle the words and make sense out of them. Resorting to mot-à-mot usually generates nonsense!

--------------------------------------------------
Note added at 15 hrs (2022-12-01 10:30:24 GMT)
--------------------------------------------------

Yes, but as I said, the insulin is not the sole purpose of the carnet; so I think it's important to read this as 'insulin as recorded in the patient's diary' rather than 'an insulin diary', if you see the distinction I am trying to make?