Objective  To identify multimorbidity patterns and major comorbidities in middle-aged and elderly patients with type 2 diabetes mellitus (T2DM) for providing evidence to the improvement of traditional Chinese health management and clinical guidelines on multimorbidity.

  Methods  We extracted electronic medical records of 21 425 T2DM patients aged ≥ 45 years and seeking medication from January 1, 2015 to December 31, 2019 in Xiyuan Hospital of the Chinese Academy of Chinese Medical Sciences. Association rule mining was used to identify common binary patterns of multimorbidity in the patients and the multimorbidity network for the T2DM patients was constructed. The major comorbidities were identified according to the network topological index.

  Results  Of all the T2DM patients, 83.3% (17 843) were diagnosed with 16 other chronic diseases. Among the 16 chronic diseases (including coronary heart disease, congestive heart failure, atrial fibrillation, ischemic stroke, hypertension, dyslipidemia, atherosclerosis, chronic obstructive pulmonary disease, asthma, chronic nephritis, chronic hepatitis, rheumatoid arthritis, osteoarthritis, osteoporosis, depression, and anxiety), totally 76 types of binary patterns of multimorbidity were found, with the most common comorbidity of coronary heart disease and hypertension (support index = 0.45, lift index = 1.31) according the rank of support index and hypertension and coronary heart disease being the diseases in 15 binary comorbidities. For the T2DM patients treated with traditional Chinese medicine, the multimorbidity network plot suggested higher multimorbidity rates among hypertension, coronary heart disease, dyslipidemia, osteoporosis and osteoarthritis diseases, indicating a complex multimorbidity relationship. In the multimorbidity network constructed, coronary heart disease and hypertension were identified with the greatest node and closeness degree (nodes = 15, closeness index = 0.45). Based on the degrees of node, strength, closeness and eigenvector centrality, hypertension, coronary heart disease, dyslipidemia, osteoarthritis and osteoporosis were at the key positions in the multimorbidity network constructed and were the major comorbidities among the T2DM patients.

  Conclusion  Among middle-aged and elderly patients with type 2 diabetes mellitus, hypertension, coronary heart disease, dyslipidemia, osteoarthritis and osteoporosis are the major comorbidities and the comorbities need to be concerned for effective prevention and management on multimorbidity in the patients.