Objective Meta-analysis was used to summarize the current status of medication adherence in patients with type 2 diabetes mellitus and to clarify the characteristics of people with low medication adherence.Methods Relevant literatures were searched in Pubmed,Cochrane Library,Web of Science,Embase,CINAHL,CBM,China National Knowledge Infrastructure,Wanfang Data,and VIP.Two researchers conducted literature screening,data extraction and quality evaluation.Stata 16.0 software was used for subgroup analysis,sensitivity analysis,offset analysis.Results A total of 42 papers were included,and the overall medication adherence of middle-aged and elderly type 2 diabetes patients ranged from 18.37%-96.53%.The medication adherence was higher among those with high education level(63%),married(61%),not living alone(50%),monthly income>3000 RMB/month(64%),having medical insurance(49%),good psychological status(61%),no chronic co-morbidities(66%),having knowledge about the disease(53%),taking≤3 types of medication(58%),convenient access to medical care(58%),and good doctor-patient relationship(50%).Conclusion The medication adherence of patients with type 2 diabetes mellitus varies greatly among different subgroups.In the future,the specific influencing factors should be further explored to formulate targeted policies and intervention measures to improve patients'medication adherence and improve their health and quality of life.