This is a hypothesis that I cannot prove but that I think may be true.
While in honeymoon, different basal levels across a fairly broad range may be chosen and still appear to work (whereas, after honeymoon, only one basal level will work: that part I think we know already).
For instance, let’s say that you really need 1U/hour, but your beta cells can only provide 0.8U/hr (a highly simplified analysis for the sake of this logical argument). It is possible that you may be able to pick 0.2U/hr, 0.5U/hr, or 1U/hr for your exogenous basal rate, and see a nice flat curve in all cases: your beta cells would likely automatically reduce their production to match just what is needed.
So where would you likely see problems, if you pick the wrong level, i.e. if you are too low? I think that you would see them during the day, after a heavy meal, where your beta cells are under pressure to produce. Or, possibly, you would see problems in times of stress.
What would happen when you get close to the end of your honeymoon?
If you are at the right level exactly, you would see less regular nights and days when your beta cells sputter and you don’t get the perfect regulation anymore, but this effect may be faint. You would also get worse peaks (or lows) after meals, because you are rarely perfect when dosing, but your beta cells make it up while on honeymoon.
On the other hand, if your level is too low, when your beta cells weaken, you may still be good at nights if you have a bit of margin (say you need 1U/hr, your beta cells used to be able to provide 0.8U/hr but now they are down to 0.4U/hr, and the level you picked is 0.6U/hr), but you will show problems as soon as your insulin production is under stress, probably after large meals, or possibly after any meal. If you don’t have any margin, when your beta cells weaken you should see highs at night right away, and problems over meals as well.
Origin of the hypothesis
What made me think of this are @kpanda01’s recent thread on late honeymoon spikes, and @Kaelan’s comment that he is now sensitive to +/- 0.05U/hr in basal. I know we were not sensitive at all to basal levels when in honeymoon, but, at the time, I thought we were just very good at picking basal Now I think that honeymoon is possibly not demanding at all on the precision of a basal choice.
If this hypothesis is right, it means that any level which, when added to the minimum sustainable level provided by the beta cells, is still higher than the actual basal requirement, will still appear to work.
But, on the other hand, it may be really difficult to figure out what the truly right level is early on. One might think that the best level to pick while on honeymoon is the highest basal that does not drive you low. But, while on honeymoon, we are still in full regulating cycle (insulin+glucagon), so it probably means that you may be able to pick too high a basal level (by a bit) and still not go low.
My guess, though, is that a higher basal level (as high as possible?) would be the best basal level to protect your beta cells for as long as possible.
I did look for research data to see if this had already been validated. I could not find anything directly proving this hypothesis. However, I did find several articles mentioning picking “the lowest possible basal” as a strategy for newly diagnosed T1Ds or for pediatric PWDs. The best one is:
This point of this article is actually surprising to me. The authors experiment with as low a basal level a possible for newly diagnosed T1Ds, and find that using as low a basal as possible actually lowers the PWD’s A1c. I have not yet been able to think of a good reason why this would happen.
A similar, but less convincing study can be seen here:
It is less convincing to me because, to read it, the authors are able to pick lower basal rates at will for patients, some of which are out of honeymoon. I don’t think this is generally possible without losing control of your BG one way or another: I think that, at any time, a T1D only has one specific basal that keeps him or her flat.
What do you think?