Blood Glucose monitors.
My Mom had three. Two by One Touch (The mini and the smart). And one Walgreen's model that we bought on a trip to WI when she forgot her meter. Yesterday, I tested with both OT meters and got readings 5 points apart. Ugh, ssn679doc was right. (doc, I will be buying calibration fluid soon.)
I recoded both One Touch meters this morning and tested using both. They now agree with each other. I plan to use the "Smart" going forward because it has a log book and graphs. The mini will be my back up.
***I am now in normal FBS range which makes me happy, but it took 4 days to get there after my last binge. There's a lesson for me.
EDIT: I set up the "Smart" to track BS, weight, & ketones. I can also input exercise, macros and notes about wellness and illness. This should be a useful device for this experiment.