Blood Glucose test strips
Basically, you can get a "control solution" (basically a "blood simulant") which contains a known level of "blood glucose", intended for testing your blood glucose meter to check that it is calibrated correctly.
Failing that, are you able to check your meter/strips against a known good machine? (at the doctor's surgery, or a pharmacy, etc?)
ie take your machine with you to the doctor's surgery, prick your finger, put some blood on a strip for your machine and some blood on a strip for the doctor's (presumably professionally calibrated?) machine, and compare the readings that both machines give?
I am expected to make life-altering decisions about my insulin dosage (too much can kill me, or me kill or hurt someone else ). If the calibration suddenly shifts to show results that are higher than actual, I am liable to think that I should over-dose.
The current strips seem to be giving more reasonable results. Thanks for your suggestions.
9.5 acres with 300-odd pines and lots of wobbly fences 
Interesting to hear that, heading off to India, I was not planning on putting them in the cool pouch with the insulin, but perhaps as I bought a large size one I should.
greenfingers wrote: Another thing to consider is that the strips degrade when the weather is warmer. I only found this out when our flatmates readings started going crazy last summer, yet when he was tested by his diabetes nurse, his levels were ok. The Diabetes nurse told him to keep strips in a cool place in the house (not refrigerated) and don't leave them in a car.
I have mentioned this before, but I have trialed it since it arrived and after one single soak in water, it kept cool for over 3 weeks! It is amazing