Background: Diabetes mellitus (DM) is a prevalent chronic disease associated with both macrovascular (e.g., cardiovascular disease) and microvascular complications (e.g., diabetic kidney disease, retinopathy, neuropathy), significantly impacting mortality and quality of life. Musculoskeletal complications, including bicipital tendinitis, are common in diabetic patients, often leading to debilitating pain and functional impairment. Non-operative treatments, including physical therapy modalities like shockwave therapy (SWT), low-level laser therapy (LLLT), and Kinesio taping (KT), are widely utilized but require further comparative effectiveness research. Methods: This study aimed to compare the outcomes of different rehabilitation programs for bicipital tendinitis in elderly diabetic patients. Eighty male subjects aged 60-70 years with clinically diagnosed bicipital tendinitis were randomly assigned to four treatment groups: exercise, LLLT, SWT, and KT. Each group underwent specific treatment protocols over an 8 week period. Outcome measures included Visual Analogue Scale (VAS) for pain, medial to lateral shoulder width, hand grip strength, and shoulder range of motion (ROM), assessed pre- and post-treatment using Musculoskeletal ultrasonography, dynamometer, goniometer, and the Older People's Quality of Life Questionnaire (OPQOL-35). Statistical analyses included ANOVA, Chi-squared test, and mixed MANOVA with Bonferroni corrections. Results: All treatment groups showed significant improvements in VAS scores (p < 0.001), with the LLLT group demonstrating the largest reduction in pain intensity. Medial to lateral shoulder width decreased significantly across all groups (p < 0.01), most notably in the exercise group. Hand grip strength increased significantly in the exercise and SWT groups (p = 0.001). Shoulder ROM improved significantly in all groups (p < 0.001), with the exercise group showing the highest increase in both flexion and extension ROM. Post-hoc analysis revealed significant differences between treatment groups for pain reduction and shoulder ROM improvements. Conclusion: In conclusion, all rehabilitation modalities (exercise, LLLT, SWT, and KT) effectively improved pain levels, shoulder width, hand grip strength, and ROM in elderly diabetic patients with bicipital tendinitis. However, LLLT and exercise showed superior outcomes in pain reduction, while exercise demonstrated the most substantial improvements in shoulder ROM. These findings support the integration of specific rehabilitation modalities tailored to individual patient needs in managing musculoskeletal complications of diabetes, highlighting the potential benefits of multimodal approaches in clinical practice. Further research is warranted to validate these findings and optimize treatment strategies for diabetic patients with musculoskeletal disorders.