I want to remind everyone that giving earlier shots is considered a dose increase, although changing in 15 minute increments is fine without needing a change in dose.
However, what if you had to do this change to 8AM TOMORROW????
Some of us had to learn how to do these type of shot schedule changes by necessity. As mentioned, an earlier shot = a dose increase. So, if you lower the dose, that should prevent any overfilling of the shed to occur. But by how much should you lower the dose?
I have become a proponent of percentage changes in dose, rather than .25 or whatever the current recommendation is. If you learn to think this way, you soon learn that just as the Tilly protocol says, if you are on a higher dose, the changes in dose will be larger. Let's review the math:
1U to 1.25U is a 25% change. 1U to 1.5U is a 50% change! Wowsa, that's a lot of added insulin. However, a change from 2.25U to 2.5U is only a 12.5% change. 2.25 to 2.75U is a 22% change, which would be more reasonable at this higher dose.
So just how would you change the dose if you had to give a shot at +9 rather than +12? First off, giving a shot 3 hours earlier is frankly playing with fire, even if it is reduced. On Levemir a shot at +9 could very well be at nadir. So if you can hold off till +10, that's better, you should be seeing a rise by that point or at least no longer falling BGs.
From my experience with Levemir, a dose reduced by 15% should be safe to give at +10. However, ECID and it would be advisable to only do an earlier shot when you can test over the next few hours and it's also only advisable if you have a decent amount of data to know when nadir occurs and generally how their cycle operates. Do they experience a sudden BG dip at +11? It can happen.
There will be BG repercussions to a dose change in time and amount, but that's life. Nothing's perfect. But it is better to give some insulin than none, even at +10.
This is what an "alternative" forum should be about - finding ways to manage the diabetes around your life, not your life around the diabetes.