We talk about Lantus being a background insulin and Humalog being a mealtime insulin. What that amount to, if the proportions of the two are adjusted property is that Humalog works to store away the glucose produced by what we eat, some to our muscles and other parts of the body that need a constant supply, and the rest going to our liver where it is turned into glycogen and waits for the times between meals when we need more fuel in the more active parts of our bodies. Then the Lantus gradually becomes available over the rest of the day to take care of the glucose released by the liver as needed.
We do know that when a person's blood glucose level drops too low, the liver releases some of its stored glycogen, turning it back into glucose, so that it can be redistributed to the cells were it is needed. We don't usually talk about it as much, but cortisol is the hormone that signals the liver to release glucose and allow it to build up in the blood so it can eventually be redistributed to the places were it is needed.
Exactly at what point does that happen? I think it is an individual thing. Sometimes, like overnight when we need enery to keep our heart and lungs and brains working, it can be a slow, steady process, and when we are getting ready to wake up, there is an increase in blood glucose supplied by the liver. I think some of us are more likely than others to begin releasing that additional glucose at somewhat higher existing blood glucose levels, and indeed, metformin is the medication that many of us take to "tranquilize" the liver so that is less likely to be sending out glucose until it is really needed.
I suppose with enough testing at the right times you could figure out at what point your liver might be going into action and raising blood glucose, but it does sound like a possibility to me. The question in my mind, then, is without metformin, what strategy or medication can you use to avoid the unwanted increase in blood glucose before it becomes mealtime? For instance, would you be better off with a slightly smaller meal and a between mean snack, with the same overall carb content, to stretch out the delivery of glucose from food? I admit I am getting out of my league, so I will wait to see what others have to say.