Objective To investigate the impact of diabetes stratification on the recovery of shoulder joint function following arthroscopic rotator cuff repair. Methods Between January 2020 and April 2024， a total of 216 patients who underwent arthroscopic rotator cuff repair at our hospital were enrolled in this study. According to preoperative blood glucose control status， the patients were categorized into four groups： Group A （non?diabetic patients）， Group B （diabetic patients with well?controlled blood glucose）， Group C （diabetic patients with mild dysglycemia）， and Group D （diabetic patients with severe dysglycemia）. All participants received standardized arthroscopic rotator cuff repair surgery and followed the same postoperative rehabilitation protocol. We assessed inflammatory factor levels， shoulder joint range of motion， Visual Analog Scale （VAS） pain scores， and Constant?Murley scores both preoperatively and at 1， 2， 3， and 6 months post?surgery. Furthermore， we examined rotator cuff thickness， axillary pouch width， and complication rates at the 6?month follow?up. A multivariate logistic regression model was employed to identify factors influencing shoulder function recovery after arthroscopic rotator cuff repair. Results At 1， 3， and 6 months post-surgery， the levels of ESR （erythrocyte sedimentation rate） and CRP （C-reactive protein） in Groups A， B， C， and D exhibited a gradual increase （P < 0.05）. Simultaneously， the shoulder joint flexion， abduction， external rotation， internal rotation， and extension angles in all groups demonstrated a gradual decrease （P < 0.05）. The VAS pain scores in Group D were significantly higher at 1， 3， and 6 months compared to Groups A， B， and C （P < 0.05）， while the Constant-Murley scores in Group D were significantly lower than those in Groups A， B， and C （P < 0.05）. No significant differences in VAS or Constant-Murley scores were observed between Groups A， B， and C （P > 0.05）. The rotator cuff thickness and axillary pouch width in Group D were significantly greater than those in Groups A and B （P < 0.05）. Furthermore， the incidence of superficial incision infection in Group D was significantly higher than that in Group A （P < 0.05）. Multivariate Logistic regression analysis revealed that age， HbA_1c levels， and complete tear were risk factors for impaired shoulder function recovery after arthroscopic rotator cuff repair （P < 0.05）， whereas early repair served as a protective factor （P < 0.05）. Conclusion Poor blood glucose control in diabetic patients markedly compromises shoulder joint function and structural recovery after arthroscopic rotator cuff repair， leading to more severe postoperative pain， a higher incidence of incision infections， and a delayed resolution of the inflammatory response.