Do you see lots of variability in insulin needs?
Yes, my insulin needs change all the time. They change based on my diet, how much I'm exercising, what kind of exercise I'm engaging in, the weather, hormones, which party is controlling Congress and/or the White House, the position of the moon relative to the earth, etc (ok, the last one is a bit of a joke, but you get the idea). There are SO many things that can change your insulin needs. Have you gained or lost any weight? There are days where I use as little as 20 units of insulin (especially if I'm eating very low carb) and days when I need as much as 45 units. It just depends. Also, I'm a woman so at certain times of the month, I'm far more insulin resistant than others.
What do you look for to gauge insulin demand?
I look for numbers that are consistently outside of my range. I don't necessarily change anything if I peak at 200 but immediately start to come back down. But, if I stay at 200, or below 70, I will start with changing my basal rate. For some reason, I have had more success changing my basal rates than my I:C ratios. For awhile I had different I:C ratios for different times of the day, but over the summer, I found that an across-the-board 1:15 ratio worked best. This may now change with the cooler weather.
What techniques do others use to adjust to fast changing insulin needs?
For me, the only thing that works is logging my numbers and looking for any kind of pattern/trend. Being on the pump has helped A TON because it is so much easier to react to changing needs in my basal insulin. I love my pump for that reason alone. I have a hectic work schedule, I travel some, and I'm very active. Being able to change a basal rate and see a result in just an hour or so is incredibly beneficial.
I use Carelink and find the reports that I generate with that system really helpful.