From a diagnostic point of view your Fasting number (FBS) gives insight into how your (system) is working when you are not shoving food in your mouth 😁

The FBS gives insight into how well you are metabolizing sugar in your system that was released as the result of varying hormone levels while you were sleeping/not eating for some period of time (6 - 10 hours for most)

If your FBS is above 126/7.0 mmols that indicates that either:

1: your liver which stores sugar for use while fasting is a little out of whack and that you either need Metformin (or a dosage increase if you are already on it) OR if you are maxed out on Metformin then a Long or Extra Long Acting (Basil) Insulin may be needed to manage; or

2: you have a possible hormone imbalance that is not related to Diabetes but that (issue) is making Diabetes management difficult or impossible so that secondary condition needs to be tracked down and treated if necessary/possible

Hormone imbalance is almost always the result of an issue with the Thyroid, Pituitary or Renal Glands - all can be medicated if they get a little whacky and in turn that will improve your blood sugar levels particularly while fasting

All your other readings during the day are heavily influenced by whatever it is that you eat "that day" and it's almost never replicated day to day

So taking a reading every day at say 8:00pm doesn't have the "clinical value" that the FBS did since that 8pm reading would be very dependent on what you did and ate that day, so comparing say 3 days is almost meaningless, where comparing FBS readings show (involuntary) trends in your blood sugar and if they get out of whack then the Doc "knows" something physiological is the reason - nothing to do with what you ate...

Hi @A DiabetesTeam Member you should take your fasting number as soon as you can after getting up before you eat/drink anything - even a good idea to do it before brushing your teeth in the morning

Many common things can elevate blood sugar after waking up, even simply getting out of bed, so the "most accurate" FBS will as soon as possible after waking up

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A Diabete...

Thanks for the valuable info Joyce and Graham.

Larry it helps determine if you are managing your diabetes

I find that my fbs nearly always affects my post meal readings for that day.

It is said that one of the reasons for high fbs is that the liver does not get a specific hormone from the pancreas telling it to stop dumping glucose in the body when it’s not needed.

The reasons for this could be fat in the pancreas blocking the hormone or as Graham Lamb suggests hormonal imbalance.

Metformin can be a help as it suppresses the liver from dumping the glucose but does not address the underlying issues.