Effects of Aerobic Exercise on Shoulder Pain, Disability, and Ultrasonographic Outcomes in Patients With Type 2 Diabetes Mellitus With Supraspinatus Tendinopathy

Type 2 diabetes mellitus (T2DM) is a chronic disease characterized by persistently elevated blood glucose levels. If left untreated, it can lead to serious long-term vascular and neurological complications. T2DM is also an important cause of morbidity due to microvascular complications, including retinopathy, nephropathy, and neuropathy; macrovascular complications, including ischemic heart disease, stroke, and peripheral vascular disease; and reduced quality of life.

In addition to its metabolic effects, T2DM has significant effects on the musculoskeletal system. Musculoskeletal disorders such as tendinopathy, entrapment neuropathies, and osteoarthritis have been reported to occur more frequently and with greater severity in patients with T2DM. Although musculoskeletal disorders in patients with diabetes have received relatively limited attention in the literature, they can contribute to both physical and psychological morbidity and substantially impair patients' quality of life.

Current evidence suggests two main pathophysiological mechanisms underlying the development of diabetic shoulder disorders. The first involves connective tissue degeneration in the rotator cuff and joint capsule, while the second is associated with peripheral or autonomic neuropathy. Recent studies have shown that advanced glycation end products (AGEs), which develop as a result of chronic hyperglycemia, accumulate in tissues and increase cross-linking between collagen fibers. This process disrupts collagen architecture and compromises the structural integrity and biomechanical properties of connective tissue .

Aerobic exercise has been shown to be one of the most effective approaches for improving glycemic control, reducing cardiovascular risk factors, promoting weight loss, and enhancing overall well-being . Therefore, aerobic exercise may serve as an important adjunctive treatment in musculoskeletal rehabilitation programs for patients with diabetes. However, very few studies have investigated the effectiveness of aerobic exercise in patients with diabetes who have specific musculoskeletal disorders . Furthermore, most clinical studies focusing on shoulder rehabilitation have been conducted either in individuals without diabetes or in patients with diabetes who have a specific shoulder condition, such as adhesive capsulitis, with limited attention given to other shoulder disorders .

The limited research in this area may be partly due to the clinical prioritization of more life-threatening complications of diabetes, such as cardiovascular diseases. However, musculoskeletal disorders can reduce physical mobility, increase morbidity, and impose a substantial burden on quality of life in this patient population . Therefore, further research is needed to better understand whether adding aerobic exercise to standard shoulder rehabilitation programs can help reduce musculoskeletal complications in individuals with diabetes.

Previous studies have investigated conventional and shoulder-specific treatment approaches for various shoulder disorders in patients with type 2 diabetes mellitus (T2DM) . However, evidence regarding the effectiveness of aerobic exercise in this patient population remains limited. To our knowledge, only one study has evaluated the effects of aerobic exercise on pain and range of motion in patients with T2DM and adhesive capsulitis . The present study aims to investigate whether the addition of aerobic exercise results in significant improvements in shoulder pain, functional disability, and the structural characteristics of the supraspinatus tendon, as assessed by ultrasonography and elastography, in patients with T2DM and supraspinatus tendinopathy. The findings of this study are expected to provide scientific evidence for the development of more effective and comprehensive rehabilitation strategies for patients with diabetes and shoulder pain.

Inclusion criteria

• Aged 30-70 years.
• Having a diagnosis of type 2 diabetes mellitus (T2DM) for more than 1 year.
• Having unilateral or bilateral shoulder pain for at least 3 months and a diagnosis of supraspinatus tendinopathy confirmed by magnetic resonance imaging (MRI).
• Having a pain intensity score of ≥3 on the Visual Analog Scale (VAS).
• No participation in regular exercise during the past 6 months

Exclusion criteria

• Having received shoulder rehabilitation within the past 6 months.
• Having a full-thickness tear of the supraspinatus tendon.
• Having a history of fracture, surgery, or injection in the upper extremity within the past 6 months.
• Having a diagnosis of a neuromuscular disease, rheumatic disease, or severe cardiovascular disease.
• Having advanced diabetic complications.
• Having any condition that contraindicates or prevents participation in aerobic exercise.