Lantus peaking 3 hours after injection?

Over the past 3 weeks, we have fairly significantly increased the basal portion of the TDD, which has resulted in a lower average TDD. We have run into repeated lows in the 1:00-2:00 am time range, for almost 2 weeks on a row. At first, I attributed it to repeated evening peaks that may have been overcompensated. But the lows were often persistent lows, taking an hour or two to resolve, and using tens of grams of carbs (you will need to click on the image):

I started suspecting, after a while, that these sometimes persistent lows were linked to basal, and I started to wonder: could Lantus, which he injects around 9:30 pm, peak 3 hours later for us?

So yesterday we moved the Lantus injection time to 7:30 pm. No persistent lows last night – although we had a slight peak which may have suppressed it. It will be interesting to see the next few nights. Here is last night’s midnight track:

3 hours sounds like the right ballpark. With lantus it’s not so much a peak as when it hits full stride. It takes a few hours to be fully working. That sounds like what you are seeing.

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When I was using Lantus (injection about 11pm), I would often get lows about 4 hours later (around 3 a.m.), especially if I had been very active during the preceding day. Going on the pump has eliminated that problem, I am very grateful to say.

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