--at various times and under various circumstances. While the home blood sugar devices are not as accurate as tests done through labs, at leat you can get rough estimates, and notice any big discrepancies.
It's always possible, you know, that the 38 reading was a lab error. These do happen, and sometimes a future repetition of a test shows a more "normal" reading.
As far as Alan's spinal tap, I'm sure the doctors will want to err ont eh side of caution, meaning he will probably be monitored and allowed to lie there as long as they and both of you feel is necessary. When I had mine done, I lay still for about four hours on my back (watching TV--fortunately, I had lots of cartoons

) until I hd to get up and go to the bathroom, but I did not get a headache. (This was when I was an inpatient in SI University Hosptial in 2003, a month into my saga, getting oodles of tests performed.)
Generally, what docs look for are signs of autoimmune disease, so such as protein banding that might represent a breakdown of myelin. They will also look for excess blood cells in the fluid, or any signs of infection. Normal spinal fluid is crystal clear, cloudy fluid is suspicious. (They found absolutely nothing amiss in mine, so even a normal results doesn't necessarily rule out problems.)