Fingertip blood glucose refers to capillary whole blood, which contains more components and has more factors affecting it. It cannot be used as a diagnostic criterion for diabetes mellitus, and is generally used for daily blood glucose monitoring by patients who have already been diagnosed with diabetes mellitus. If you want to confirm whether there is an increase in blood glucose, you must take fasting venous blood glucose and 2 hours after meals venous blood glucose, venous plasma blood glucose as the standard. If a patient has been diagnosed with diabetes, they should bring their own glucose meter for daily glucose monitoring. It is recommended that before using the glucose meter, they must go to the hospital to calibrate the accuracy of the meter, take venous blood glucose and fingertip blood glucose at the same time, and compare the results of the two. If the error is not more than 1mmol/L, the accuracy of the glucose meter can be proved, if the error is too large, do not use the glucose meter.