I started pumping in 1987. Since the first rapid acting analog insulin did not come out until 1996, I used Regular insulin in my pump in the early years. I remember using a Regular insulin called Velosulin, an insulin that had some additional buffering agents added that inhibited infusion set occlusions. I may have also used Humulin (Regular) during that stretch.
I haven’t thought about this much but I currently change my basal rates two hours before I want to see my BGs change. With Regular, that lag time would be greater. I wasn’t as skilled at using my pump back then and I basically ran with a basal profile for months and months without ever altering it, so my experience with pump basal Regular insulin was not much due to my inattention.
Even today’s modern rapid acting analog insulins vary from time to time. My body does not exactly absorb insulin the same way each time. I think ( I’m speculating here.) that Regular insulin, with its longer onset, peak, and duration, would be even less repeatable and consistent.
I suppose I could do the experiment but I’m not interested in disturbing a therapy that works very well for me. If I lost access to the analogs and had to use Regular, I would figure out a way to make it work with a pump. I would definitely prefer Regular in a pump to going back to NPH. NPH was a real time tyrant when it came to feeding at its peak. I used NPH twice per day when I was on MDI before I started on a pump.