Oliver had his first recorded hypo event. He recovered quickly on his own just by eating his regular +5 hour quarter meal. Does 1 event warrant an insulin reduction?
That low of 57 tells you the 1u dose is too high. Oliver's dose should be reduced to 0.75u. Dosing is based on how low a dose takes BG while the pre-shot test tells you if it's safe to give insulin. Do you have syringes with half unit markings?
Do you have the conversion chart for the U100? HERE it is in case you need it. If you use the U100 syringe, you could draw up to just a smidge above (toward the needle) the 2.0 line between the 2.0 and 1.5u lines.
That's a great question! One hypo doesn't necessarily mean a reduction. If it's an anomaly (a strange dip in an otherwise generally high sea of data), or if it's a long-term diabetic kitty, then sometimes they just need to be ignored. However, given the surrounding numbers on your spreadsheet, I agree with Linda that a reduction is warranted in this case.