Introduction
There is increasing evidence on the association between type 2 diabetes mellitus (DM) and osteoarthritis (OA). Subjects with diabetes are nearly twice as likely to have OA and arthroplasty than subjects without diabetes, independent of age or body mass index (BMI).1–4 It has been suggested that subjects with both DM and OA have more severe symptoms.2 DM and insulin resistance have been considered as prognosticators of joint space narrowing and knee OA only in males.3 4 This difference concerning male gender, DM and OA especially regarding pain symptoms has not been fully investigated.
Patients with OA and diabetes might experience more intense pain than non-diabetic patients and it is unknown whether there are joints that could be more affected than others. Pain in non-weight-bearing joints, such as hand joints, in patients with DM and OA, might especially reflect involvement of neuropathic complications of diabetes in the source of OA pain.5
Enriched insulin receptor (InsR) expression has been demonstrated in the synovium of humans.6 7 In addition, it has been suggested that long-term insulin therapy, often needed to treat diabetes, may overload tissues such as cartilage.8 It is still necessary to know whether the glycemic control done through medications or simply if elevated insulin levels can influence the perception of OA pain in patients with diabetes. We aim to investigate differences in pain severity (level of pain reported, localization and number of joints affected by pain) between patients with and without DM in a population with advanced OA. We want to determine whether these differences exist for both genders. In addition, we would like to explore the role of medication used for diabetes in these associations.