Increased risk of shoulder calcific tendinopathy in diabetes mellitus: A nationwide, population‐based, matched cohort study

Background Calcific tendinopathy of the rotator cuff is a common cause of painful disability in the shoulder with unclear aetiology. Diabetes mellitus (DM) is associated with calcific tendinopathy; however, large epidemiological data are lacking. Thus, we conducted a nationwide population‐based matched cohort study to investigate the risk for calcific tendinopathy of the shoulder in diabetic patients. Methods The National Health Insurance Research Database of Taiwan was used to include 42 915 patients newly diagnosed with DM between 1 January 2000 and 31 December 2015 and randomly extract the data of 171 660 individuals, as a matched control group. All individuals were followed‐up until the development of calcific tendinopathy or the end of 2015. Results Overall, 122 patients from the DM group (0.284%) developed calcific tendinopathy compared with 340 individuals from the non‐DM group (0.198%). The Kaplan–Meier analysis indicated that patients with DM had a higher risk of calcific tendinopathy since the eighth year of follow‐up (log‐rank test, P = .006). Cox proportional hazard regression revealed that the adjusted hazard ratio of calcific tendinopathy in diabetic patients to that in non‐diabetic patients was 1.276 (95% confidence interval 1.037‐1.571, P = .002). Moreover, the stratified analysis disclosed that DM was a strong independent risk factor for calcific tendinopathy irrespective of the existing comorbidities. Conclusions This study demonstrated that patients with DM had a 27% increased risk of developing calcific tendinopathy of the shoulder, 8 years after initially being diagnosed with DM.