Background: The association between substances use disorder and type 2 diabetes mellitus, is an under-studied topic. Since type 2 diabetes is a major health issue, it requires a comprehensive knowledge of all aspects regarding its etiology and risk factors. Objective: To understand the association between different substance abuse and type 2 diabetes among patients admitted to the Ministry of Health (MOH) addiction hospital in Jeddah, Saudi Arabia.Methods: This is an analytical cross-sectional study. Data were retrieved from the patient's records over the year of 2021. Random sampling was applied to include the patients. The data collection sheet was created by the researcher.Data analysis was done using the statistical package for the social sciences (SPSS, version 27.0). Results: A total of (322) patients were included in the analysis. Amphetamines were the most common used substance 55.3%, followed by Cannabis 53.1%. Of the total, 8.4% had diabetes. Two thirds (66.7%) were taking medications, and only three cases (1.1%) had controlled blood glucose levels. Among those whom diabetes was not controlled, the HbA1c mean was 9.9%±1.6. Regarding other comorbidities, 11.1% had psychiatric illnesses, 2.5% had hepatitis C virus and 1.2% had HIV. Longer durations of abuse and Cannabis use were significantly associated with diabetes (P-value=0.02, P-value<0.001), respectively. Conclusion: The prevalence of diabetes among substance use patients was (8.4%), and the majority of which had uncontrolled blood glucose levels. While most substances were not associated with diabetes, cannabis showed a significant association in our sample.