Caught completely offguard by a lack of insulin resistance

[imsweetenough]

This has never happened to me before. I was at 14.2 at 09.29 when I took 72 units of M3 Humulin. I normally take 80 but couldn't be bothered starting a new pen and taking a second injection. Then I jumped into a conference call. Normally I won't see a below 10 reading until after 2pm if I don't eat and after 4 if I do. At 10.20 my hypo alarm went off and I was at 3.6 dropping vertically. I have never had a drop like that before. I took me completely by surprise. It's like I have virtually no insulin resistance this morning but can't really work out why that is. Still spectacularly overweight. Anyone else have weird days like this?
T2 since around 5 years old
Age 52 male
M3 Humulin twice daily