OBJECTIVE: To examine the association between shoulder capsulitis and chronic diabetic complications and diseases closely related to diabetes. METHODS: A cross sectional study in 291 type I [mean (SD) age 33.2 (9.9) years] and 134 type II [61.1 (12.4) years] diabetic patients. The presence of shoulder capsulitis, Dupuytren disease, and limited joint mobility was sought. The patients were assessed for background and proliferative retinopathy, nephropathy, autonomic neuropathy, and peripheral symmetrical somatic polyneuropathy. Diseases closely related to diabetes (hypertension, history of myocardial infarction, coronary heart disease, and peripheral vascular disease) were also recorded. RESULTS: Prevalence of shoulder capsulitis was 10.3% in type I and 22.4% in type II diabetic subjects. Shoulder capsulitis was associated with the age in types I (P < 0.01) and II (P < 0.05) diabetic patients, and with the duration of diabetes in type I patients (P < 0.01). Odds ratios for autonomic neuropathy in type I and type II diabetic subjects with shoulder capsulitis were 4.1 (95% confidence interval, 1.6 to 10.9) and 2.7 (95% CI, 1.1 to 7.0), respectively, after controlling for age and duration of diabetes. Odds ratio for history of myocardial infarction in type I diabetic subjects with shoulder capsulitis was 13.7 (95% CI, 1.3 to 139.5) after controlling for age, duration of diabetes, hypertension, and smoking habits. Other associations between shoulder capsulitis and diabetic complications, related diseases, and other hand abnormalities were fully explained by age and the duration of diabetes. CONCLUSIONS: Shoulder capsulitis is common in type I and type II diabetic patients. It is associated with age in type I and II diabetic patients and with the duration of diabetes in type I patients. It is associated with autonomic neuropathy in type I and II diabetic patients and with history of myocardial infarction in type I diabetic patients, independently of time related variables.