Steve Cooksey is really doing a bang up job meticulously testing resistant starch as a diabetic, and getting the word out to other diabetics.
His most recent post is to compare 30 days of overnight blood glucose readings pre resistant starch supplementation and then post. What he did was first to record 30 days of readings and chart them.
It's very well regulated, actually. So, then he took 4TBS per day of Bob's Red Mill Potato Starch for a month in order to acclimate to it before beginning another month long test of recording overnight readings to compare.