Objective The purpose of this systematic review was to evaluate the effect of different lengths of use of continuous glucose monitoring（CGM） system on glycaemic control in patients with diabetes,compared with routine nursing or self-monitoring of blood glucose（SMBG）. Methods 8 Chinese and English databases,such as PubMed,Web of Science,Cochrane Library and Embase,were searched to include randomized controlled trials on the effects of CGM on glycated hemoglobin（HbA1c）,time above range（TAR）,time in range（TIR）,time below range（TBR） and mean glucose level（MG） in diabetic patients. The randomised controlled trials were collected from inception until August 2021,and the meta-analysis was performed using RevMan 5.4 and Stata 16 software. Results A total of 11 publications were included,including 1 745 diabetic patients. The >16 weeks[MD=-0.23,95%CI（-0.35,-0.11）,P<0.001] and ≤16 weeks[MD=-0.40,95%CI（-0.42,-0.38）,P<0.001] glycated hemoglobin levels in diabetic patients using CGM,>16 weeks[MD=91.53,95%CI（65.77,117.28）,P<0.001] and ≤16 weeks[MD=128.68,95%CI（112.95,144.42）,P<0.001] glucose time in range,>16 weeks[MD=-45.10,95%CI（-76.34,-13.87）,P=0.005] and ≤16 weeks[MD=-80.37,95%CI（-96.05,-64.69）,P<0.001] glucose time above range,>16 weeks[MD=-31.83,95%CI （-44.11,-19.54）,P<0.001] and ≤16 weeks[MD=-20.90,95%CI（-37.45,-4.35）,P=0.010] glucose time below range,and ≤16 weeks mean glucose levels[MD=-0.40,95%CI（-0.54,-0.26）,P<0.001] have statistically significant differences but no statistically significant difference for >16 weeks mean glucose levels[MD=-0.22,95%CI（-0.48,0.04）,P=0.090]. Conclusion CGM was able to reduce HbA1c,increase TIR,and reduce TBR and TAR to improve glycaemic control in diabetic patients at different durations of use. As the duration of use increased,the improvement in TBR was more significant,while the improvement in HbA1c,TIR,TAR and MG gradually decreased,but the effect on long-term MG improvement was not significant,and more high-quality studies are still needed to further prove this.
