Diabetes mellitus affects the prognosis of frozen shoulder

INTRODUCTIONThe aim of this study was to establish whether diabetes mellitus (DM) affects the prognosis for patients with a frozen shoulder. METHODSIn this prospective two-year follow-up study, we included 235 patients with newly diagnosed unilateral frozen shoulder. Among the 235 patients, 34 (14%) were diagnosed with DM prior to their inclusion in the study. Patients were asked to fill out a questionnaire at the time of diagnosis and at six-, 12- and 24-month follow-ups. The questionnaire included the Oxford Shoulder Score (OSS) and a visual analogue scale (VAS) for both maximum and average daily pain. DM status was recorded for all patients and glycated haemoglobin was measured for patients not diagnosed with DM. RESULTSOverall, patients with and without DM had a similar OSS (p = 0.22) and VAS score for maximum (p = 0.46) and average (p = 0.46) daily pain at the time of diagnosis compared with patients without DM. Both groups improved their OSS and VAS score, but patients with DM had a poorer OSS at the six-month (p = 0.04) and 24-month follow-ups (p = 0.02); poorer VAS scores for maximum daily pain at the six-month (p = 0.04), 12-month (p = 0.03) and 24-month follow-ups (p = 0.03); and poorer VAS scores for average daily pain at the six-month (p = 0.02) and 12-month follow-ups (p = 0.01). CONCLUSIONSThis study shows that patients with frozen shoulder may expect a gradual improvement of both pain and movement during a two-year follow-up, but also that having DM is associated with a poorer prognosis. FUNDINGnone. TRIAL REGISTRATIONNCT01978886.