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.