Background: Frozen shoulder is a painful condition that can lead to longterm disability. The frequency of frozen shoulder among diabetic patients is about 10% to 39%. Diabetics have a higher prevalence of frozen shoulder than the general population, and these individuals are less responsive to therapy and have a larger range of motion limitation. Aim: The aim of this thesis is to determine the prevalence of diabetes among patients with frozen shoulder and to compare them in terms of demographics, clinical and treatment features. Method: This study was performed on patients who had been diagnosed with frozen shoulder at an orthopedic center in Mashhad, Iran, from 2012 to October 2021. The frequencies and cross tabulations were used to analyze the data by SPSS to determine the significance of relationships. The chi-square and t-tests have been used with a p-value less than 0.05 as the alpha level of significance. Results: Among the patients, the average age was 56 years old. Among 310 patients with Frozen shoulder, 36% were diabetic. There was no statistically significant difference in gender and level of activity between patients with and without diabetes. In contrast, the side of the affected shoulder, duration of frozen shoulder, stage of frozen shoulder and treatment of frozen shoulder were statistically significantly different between the two groups (p < 0.001). There also were statistically significant differences between treatment of frozen shoulder in patients with good and bad control diabetes groups (p < 0.001). Conclusion: Based on this study, around one-third of frozen shoulder patients have diabetes. Although there was a statistically significant difference in the treatment of frozen shoulder between patients with and without diabetes groups, diabetic individuals have a more severe course of illness, and their treatment is less effective.