Associations of renal dysfunction and neuropathy with supraspinatus tendinopathy in diabetes mellitus

Aims: Diabetes mellitus is a well-recognized risk factor for rotator cuff pathology, yet the specific clinical and metabolic determinants of tendinopathy in this population remain poorly defined. This study aimed to identify the ultrasonographic, biochemical, and clinical factors associated with the development of supraspinatus tendinopathy among patients with diabetes. Methods: We performed a single-center, retrospective cross-sectional study of 63 patients with diabetes mellitus. All participants underwent shoulder ultrasonography to measure supraspinatus tendon thickness and assess tendinitis. Patients were grouped according to ultrasonographic evidence of tendinitis. Demographic data, glycemic parameters [hemoglobin A1c (HbA1c), fasting glucose], renal function indices [estimated glomerular filtration rate (eGFR), creatinine], lipid profiles, and diabetic complications (neuropathy, retinopathy, nephropathy) were compared between groups. Logistic regression and ROC curve analyses were used to identify and evaluate diagnostic predictors.Results: Supraspinatus tendinopathy was present in 29 patients (46%). Compared with patients without tendinitis, affected individuals had significantly greater supraspinatus tendon thickness (7.66±1.29 vs. 6.95±1.22 mm; p=0.03), lower eGFR (p=0.005), higher serum creatinine (p=0.03), and a higher prevalence of diabetic neuropathy (65% vs. 35%; p=0.02). Although tendon thickness correlated positively with body mass index, HbA1c, and C-reactive protein, these metabolic and inflammatory markers did not differ significantly between groups. ROC analysis showed supraspinatus tendon thickness had the highest diagnostic accuracy (AUC=0.70).Conclusion: In our study, supraspinatus tendinopathy in diabetes mellitus was associated with tendon thickening, renal dysfunction, and neuropathy rather than glycemic or lipid measures, highlighting microvascular complications as key drivers of diabetic rotator cuff tendinopathy.