The re-test was to see if he was rising and if so, it might have been safe to shoot. The interesting thing with Lantus is that as you accumulate test data, you can shoot low to stay low. Until you have that mid-cycle test data, though, you just don't know enough about how your cat responds to the insulin.
Understanding the spreadsheet/grid:
The colored headings at the top are the ranges of glucose values. They are color-coded to clue you in as to meaning.
Each day is 1 row. Each column stores different data for the day.
From left to right, you enter
the Date in the first column
the AMPS (morning pre-shot test) in the 2nd column
the Units given (turquoise column)
Then, there are 11 columns labeled +1 through +11
If you test at +5 (5 hours after the shot), you enter the test number in the +5 column
If you test at +7 (7 hours after the shot), you enter the test number in the +7 column
and so on.
Halfway across the page is the column for PMPS (evening pre-shot)
To the right is another turquoise column for Units given at the evening shot.
There is second set of columns labeled +1 through +11
If you snag a before bed test at +3, you enter the test number in the +3 column.
We separate day and night numbers like that because many cats go lower at night.
It is merely a grid for storing the info; no math required.