With the limited amount of test data you have for Marley, the skipped dose was a good decision.
When people are first starting out, and may not know how their cat reacts to a particular dose of insulin, we have them use what we refer to as a "shoot/no shoot" BG number. Also called a "threshold" or "stop and think about what to do number" or a "decision point" number.
For Lantus insulin and for new members on the message board, that "threshold" BG level is 200.
When you start posting over on the Lantus ISG (Insulin Support Group), or even perhaps when you are still on the Main Forum, that "threshold" BG level is set at 150.
As you gain experience and gather more BG (blood glucose) test data, that decision point number drops lower and lower. It's how we get cats regulated and even to remission.
There are 3 options for when you get a pre-shot BG test that is lower than you expected.
Stall, reduced dose, or skip. See this document for an explanation.
Sticky Dosing Methods: Start Low, Go Slow (SLGS) & Tight Regulation (TR)
Lantus insulin has what we call a "depot" or storage area and the dose you give in one cycle, will take some time to fill that "depot" area. Lantus forms crystals underneath the injection site, and then is slowly absorbed and gets into the bloodstream. It's why Lantus has that nice shallow curve and longer duration than some of the in-and-out insulins. It's also why you do not want to rub the injection spot after the dose of insulin is given.
Needed to talk about that "depot" so you would understand the next part.
When you change the dose, by skipping the shot, reducing or increasing the dose, it takes a bit of time to see the full effect of that dose change. Some of the insulin given goes into that "depot" area and it takes time to fill the depot with dose increases. Conversely, even if you have skipped the shot of insulin, there is still some insulin being released from that "depot" storage area.
So, even with a skipped shot, like this morning, you should do some BG testing in this AM cycle if you are around to do that. A +2 or +3 would be good to obtain. Another test around the +6 time frame would be good. Maybe a +5 or +7 one cycle, a +4 or a +8 another cycle.
Testing at night is important too, as many cats are more active then. They "burn off" or use up some of that glucose in the blood stream as energy, and often drop lower at night than they do during the day.
Cats nadir, or reach their lowest BG levels at different times. The nadir does not always stay at the same time either, from cycle to cycle.
So testing, to see when your cat Marley has his nadir is important. ECID Every Cat is Different, Every Cycle is Different, Every Caregiver is Different.
We know that people have full and busy lives, between work and all their other responsibilities. So if something we said is not possible for you to do, let us know and we will suggest alternatives.
There are some wonderful "Sticky" posts over in the Lantus ISG forum. They are all located at the top of the forum and can help you with a more in-depth understanding of what I have said.
Hope I did not give you too much information (TMI). There is a lot to learn. We'll help you all we can.
p.s. Forgive me for oversimplifying some. There are lots of people that "lurk" or watch behind the scenes before they join the forum or create their own first post.