The biochemical instrument in the hospital has strict procedures and quality control standards for detecting venous blood sugar, which is more accurate. The diagnosis of diabetes is based on venous blood glucose, and the blood glucose measured by portable blood glucose meter can not be used as the basis for diabetes diagnosis. Because the accuracy of blood glucose meter is affected by temperature, humidity, self-stability and sensitivity, the measured blood glucose value may be different from that measured by biochemical instrument. The blood sugar values measured by some blood glucose meters fluctuate greatly. It is a way to take the blood glucose meter to the hospital and compare it with biochemical testing, which can be combined with standardizing the testing process of the blood glucose meter (see point 5); 2-3 months to check glycosylated hemoglobin, evaluate blood sugar control, and try to reduce possible errors.