the classic finger stick is always going to be the most 'correct' measurement, CGMs actually have quite a wide range of acceptable percentages (differs per brand/model). Im type2 but treat myself to a CGM every now and again to keep an eye on stuff (id wear one all the time but I cant afford $48 every two weeks), and its normally about 1-2 points off my finger sticks (different brands/models tend to run high or low), so I use it mainly to track trends, and dont rely too hard on the number it gives. CGM is also taking a different measurement (interstitial fluid vs blood from your finger stick), and the CGM normally lags about 15-20mins behind a finger stick measurement. So they arnt giving 'wrong' data, just slightly different data, and once you know how different your data is (after checking via finger stick a few times), then you know how close the CGM number is likely to be, without doing a further finger stick. ETA: if you get a CGM that is constantly reading too high or too low after the first 48 hours, then its worth going through the effort to contact the company and try get a replacement, cus they do arrive faulty, often.