BG control can be defined as "trying to keep BGs within or as close to a normal (i.e. non-diabetic) range as possible." Bearing in mind that "as close as possible" varies from one person and one situation to another, and almost no one is able to keep their BGs in normal range all the time. Some people almost never see normal range in spite of their best efforts. In fact, I feel that "control" is a bit of a misnomer, because there is a lot that goes into BG that we don't control - but, of course, a lot that we do, too. So it's more about managing BGs, that is, making the appropriate choices about things that are within our control so that we optimise the amount of time we spend with BGs in or closer to normal range.
Normal, non-diabetic range is 4-6 (well, actually 3.5 to 6, clinically speaking, but for those of us on insulin or sulfonyureas like Gliclazide, anything below 4 can be counted as a hypo, so "4's the floor" as they say!)
However, in addition to simply "getting low numbers," the goal is also to reduce spikes as much as possible. It's much better overall for your body if your BG stays relatively level, even if it's staying level at a slightly higher BG than you wanted, than for your BG to suddenly shoot up and then come back down. The real goal then is to aim for as gentle a curve as you can get (because it's almost impossible to get NO change after eating, but usually a change of 2-3 points or so is acceptable to most people - ideal for some!), and in so doing spend as much time as possible with the numbers closest to 4-6 that you can manage.
A "good" A1c is not the goal, it is only a way of measuring. In fact, it is a very blunt instrument and is best considered as merely another tool in your arsenal of assessment, rather than the last word on the state of your diabetes. There are two main reasons for this. (1) It is not only an average, but a weighted average. That is, while technically an A1c test gives you the average glycation (exposure to glucose/sugar) going on in your blood for the last 3 months, in fact the past 2 weeks or so before the test are MUCH more heavily represented than whatever was going on 3 months ago. This is because while almost all of the red blood cells in the sample will have been around for the past week or two, only a few old, decrepit ones from 3 months ago are still left floating around. What this means, practically speaking, is that if your control the past few weeks hasn't quite been up to snuff (say you had a cold or something recently) but was excellent before that, your A1c might trend higher than a "flat average" would have (unfortunately, no "flat average" test exists, and averaging your BG readings for the past 3 months won't work, because those are spot checks - they don't measure continuously the way an A1c does). Inversely, if you had really tightened up control lately, but things weren't going so well two or three months back, your A1c will trend lower than what was actually happening inside your body.
(2) The A1c is, well, an average. Imagine that your blood sugars for the past 3 months were distributed equally across a range from 4.0 to 12.0, giving you an average BG of 8 (an A1c of 6.6% or 48.6). Imagine, on the other hand, that your blood sugars had consistently remained between 7.5 and 8.5, also giving you an average BG of 8 and the same A1c. However, the second scenario indicates much better control because BGs are more stable, if slightly above goal. So an A1c can be good for showing you general tendencies (a higher A1c necessarily means that you are having higher BGs at least some of the time, for example) but it isn't good for a fine analysis and can even mask certain problematic situations (a lower A1c doesn't automatically mean better control).
As for the breakfast issue! Just as not all carbs are created equal, neither are all the times at which you could eat them. The various hormones that regulate insulin resistance/carb sensitivity (two sides of the same coin) fluctuate as part of the normal circadian rhythm of the human body, in the same way that melatonin levels fluctuate and regulate the sleep cycle. For 80-90% of people this means that they are most carb-sensitive in the morning, least carb-sensitive in the afternoon, and somewhere in the middle in the evening. This means that you generally need more insulin for the same amount of carbs taken at breakfast than you would taken at lunch or dinner - regardless of whether that insulin is coming from an injection or from your pancreas! But if you only have the insulin your pancreas can make, and your pancreas is limited in what it can produce already, this means that taking in too many carbs at breakfast might leave it unable to keep up - and thus leave you with higher BGs than if you'd eaten the same carbs later in the day.
So I - and most others here, I think - would completely agree that it's ok and even necessary to have some carbs, and to have treats! The point of staying healthy is to enjoy life, after all
And you will never be able to have a zero-carb diet anyway because there's even carbs in things like lettuce and broccoli. But for most people, whatever carbs they're having in their day, breakfast is the worst possible time to choose to incorporate them! So a lot of us aim for an all-protein breakfast and save our carbs for later in the day.
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