I have now had a chance to have a proper look at both your curves. The 8 August curve shows a typical caninsulin curve with a smile shape with the low between 4 and 6 hours post shot from a start point around 20 finishing around the same. I use a pet meter so find it difficult to 'translate' where in the normal ranges we use what the corresponding would be on a human meter.
The 25 July curve shows something different. There was a steep drop to +4 then a sudden upturn in the curve to +5 and +6 with a rise after to an end point of just under 20 from a start point of around 16, this looks to me like a bounce but I would appreciate some other eyes on this to check. Was there anything different between these 2 days - amount of food, timing of shot in relation to food, etc?
You also say you skipped the pre-shot am test yesterday, cats can throw odd numbers, and mine seems to be an expert at this, even with everything else fully controlled, so we don't know the start point yesterday. You should always test before giving insulin and when the cat has not eaten for at least 2 hours prior. It's all about getting into a regime. Mine knows no test, no food, now so she actually goes to her test place and waits for me first thing in the morning - evenings she hasn't quite got the message yet but if you have a specific test spot and give a small treat post test they do learn.
We can help you through this, bounces happen, the important thing is you recognise it, sometimes it takes a few days if you can't get mid cycle tests - life gets in the way. Regulation takes time and slow and steady is the way.
About hypos. They happen, insulin is a hormone, every cat is different, every cycle is different. Here are some links to help you
http://www.felinediabetes.com/FDMB/threads/how-to-treat-hypos-they-can-kill-print-this-out.15887/
http://www.felinediabetes.com/FDMB/threads/jojo-and-bunnys-hypo-tool-box.2354/
Come back with any questions, and welcome to the board!