Despite my consultant not being able to answer the question about how is it possible to have LADA (i.e. insufficient insulin is causing the high BS) but normal C peptide and giving me fudge answers, I think I may have worked it out:
There are 2 ways to do a C peptide test - fasting and stimulated (after eating). When your C peptide test is done, it is usually fasting. At diagnosis that will likely be with very high BS. A non diabetic would have a fasting BS of say around 5, as you haven't eaten the insulin demand is at it's lowest. The amount of C peptide produced would normally fall within the ranges they give you.
BUT if you do the test and your BS is much higher (mine was around 12) that is higher than a non diabetic would ever go even after eating a heavy carb meal, so your pancreas is constantly trying to release insulin and bring that down, so it's at maximum insulin demand not minimum. So therefore the result should be compared to normal ranges of stimulated C peptide, not fasting. Like a non diabetic who has just eaten a really sugary or carb heavy meal. The stimulated range can go much higher, my consultant said to 6000 or beyond. So my result of 1080 is completely normal when compared to fasting C peptide ranges, but on the low side when compared to stimulated ranges. Hope that makes sense!
With the insulin, my experience is the long lasting insulin kept giving me hypos overnight, not the bolus. It never happened that I dosed for the meal and my own insulin overshot it and hypo, I don't think it works like that. If insulin is detected the pancreas doesn't ignore that and try and produce the equivalent amount itself. As long as you dose correctly, it stays in range fairly easily. I had insulin for 4 weeks, only 1 week of long acting because it made me feel terrible, then 3 weeks of just bolus which was better. And 8 months since with no insulin or anything, although it may be time to add a little back in. The vast majority of LADAs are on some insulin in the honeymoon, it's only when you have very little production that it's over and you are 100% insulin dependant.
Not sure I buy that - I've been very low insulin for the entire year, meaning that the way I've been eating is entirely about
not stimulating insulin - on my recent test of this with a CGM, every single raise in blood glucose was as a result of doing something, never on account of eating something. Thus, my C-Peptide should be very small right now, whether I've eaten or not.
However - this time last year - my "normal" levels of both blood glucose and circulating insulin were much, much higher, so even in a fasted state (at least my understanding of what a fasted state was last year - really meaning "in the morning after a normal sleep") my insulin levels would have been sky high compared to now.
Fundamentally, C-Peptide is just a measure of whether the pancreas is capable of producing insulin - the C-Peptide itself is just a byproduct. Think of a rugby post. The construction of insulin is like the two posts and the cross-bar. Once they are assembled, the body discards the cross-bar, and the two posts go off to do all the things insulin does. That discarded cross-bar is C-Peptide. So - the test shows up any insulin made, not injected. The timing then is more about how long your body takes to clear up the discarded bits than it is about the rate of production of insulin - though clearly it should be highest shortly post a heavy carb meal - regardless of your insulin sensitivity.
I was explicitly asked to have a heavy-carb meal, then take urine about 2 hours after, and this was the basis of my C-Peptide. I was also injecting, and the purpose of the test was to see whether I was really T2 (which you will know I was from the other thread).
It's kind of the same discussion - and I had some pretty edgy conversations with my specialist consultant, I can tell you.... though I do feel conflicted about it, we disagreed on a lot, but I very definitely credit her with saving my life... anyway, my thought was - look, this test shows that my pancreas is still working... indeed, some of the responses I was seeing on my CGM just could not make sense if there wasn't some endogenous insulin... so that being the case, I know that I can safely reduce my insulin level (ie, being free of the concern of ketoacidosis, which seemed to be the major concern among my support team, but I knew that I hadn't seen any sight of a ketone at that point) -
Therefore, for me - it stopped being a question of "how can it be a form of T1 with high C-Peptide" - it was just insulin resistance, like everyone else.
I'm personally suspicious about the "honeymoon" thing, because I was on that track - once you start with insulin, you can (I did) find that the dosage started to go up - which would be consistent with a honeymoon period coming to an end - but it was just that I was taking in too much, which was increasing the circulating insulin, thus exacerbating the insulin resistance...
The support team are only (in my experience) focused on whether your blood glucose is in range - and it probably will be with sufficient insulin - but you will not be doing yourself any favours by having high circulating insulin. The medical doctrine is to control glucose, but as a person, if you can do it safely - there are significant benefits to bringing the insulin level down.
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