David Mendosa reviewed some reviews on home blood glucose monitor accuracy and reproducibility. He was motivated by a recent review in Consumer Reports. You’ll want to click through his links for details. The last time I looked into this, I learned that a device could receive FDA approval if it could measure accuracy to within 20% of the actual blood sugar value as determined by a laboratory machine. For a blood sugar of 200 mg/dl (11.1 mmol/l), the home device could give you a value anywhere between 160 and 240 mg/dl (8.9 to 13.3 mmol/l). That doesn’t exactly inspire confidence, does it?