Im sorry Claire, I should have made a distinction. Type one users have a very different agenda when taking BG readings. The typical type 2 user takes a reading and goes "hmmm thats nice - maybe I shouldn't eat pizza next time" and they go merrily on their way.
The Type 1 person actually uses that reading to determine an insulin load and to adjust and subsequent doses. A type one is really concerend with the starting point (prior to a meal) and then DEPENDING ON THE INSULIN, the ending point.
What do we mean depending on the insulin? Well, Humolog or Novolog users have extremely fast acting insulins that fall off very quickly after a meal. They are great for use with Lantus a long acting insulin. But if you use regular insulin it peaks in your system and lasts for MUCH longer than the fast acting stuff. Once injected, Regular insulin takes 30 minutes to begin working, peaks between 2 and 4 hours and hangs on for 6 to 8 hours, long after the meal stopped raising the blood sugar. Humalog and Novolog, on the other hand, begin working in about 10 minutes, peaks at one to one and a half hours and are gone in about three and a half to four hours.
So what does all this mean?
- If you are using one of these FAST acting insulins, testing at 90 minutes is important for determing your "lows" after a meal and making sure you don't go hypoglycemic. 90 minutes is when these insulin's peak in your body.
- With regular insulin it is much slower, needing 30 minutes just to begin to work so at 2 hours you are still not at the peak for that injection (but its a much better time to test than at 90 minutes).
The point is that Type 1's use these readings to determine what the insulin is doing to them and how to adjust their doses. Type 2's on the other hand are using the readings purely for informational purposes and may make some longer term adjustment that may or may not affect BG.
Therefore, depending on your insulin type, do your readings accordingly. I hope this helps a murky subject.