【Abstract】 Objective To analyze the patients with impaired fasting glucose under different criteria for the diagnosis of different time points after a meal, the changes of blood glucose and insulin levels and provide a basis for screening and early prognosis of prediabetes populations. Methods The participants' blood samples after a meal 2 h, 4 h, 6 h, 8 h, participants' blood glucose and insulin values were observed. The relationship between blood glucose and insulin of IFG patients diagnosed by different standards was analyzed. Results The difference between IFG patients’ age, gender, BMI, WHR, systolic blood pressure and diastolic blood pressure diagnosed by two standards had no statistical significance (P＞ 005). The heart rate was statistically significant. The WHO standard diagnosed patient's heart rate was higher than the ADA’s. The difference among different measuring time points of GLU, INS results had statistical significance (GLU:WHO,F=501,P=00005; ADA, F=374,P=00049; INS: WHO, F=688331,P＜00001; ADA, F=69621,P＜00001;). There was a negative correlation relationship between fasting blood’s glucose and insulin (WHO, r= 07227; ADA, r= 06780), and a positive correlation relationship between postprandial 4h blood’s glucose and insulin level (WHO, r=04985; ADA,r=03989). The difference was statistically significant, in two kinds of diagnostic criteria’s IFG patients. Conclusion The cut of tangent point of fasting plasma glucose will early recognize the people with prediabetes and help to take timely intervention measures and prevent progression to diabetes.