Prostate cancer (PCa) is the most common cancer in men in the US and androgen deprivation therapy (ADT) is the most frequently used systemic therapy for PCa. Data suggest that ADT is associated with an increased risk of new-onset diabetes mellitus (NODM) and cardiovascular complications. As the incidence and mortality of PCa are highest among the African American (AA) population, it is important to evaluate the difference in the incidence of NODM and ischemic heart disease (IHD) between AA men compared to Caucasian men. This is a retrospective cohort study utilizing the TriNetX database to assess NODM and IHD risk, risk difference, and risk ratio (RR) after recent ADT initiation in an AA cohort and a Caucasian cohort of patients with PCa. Propensity score matching (PSM) was performed by age, BMI, and confounding comorbidities. After matching, the cohort included 1159 AA patients and 843 Caucasian patients with NODM after ADT initiation. The IHD cohort included 1269 AA patients and 1248 Caucasian patients. The risk of incidence of NODM is higher among AA men at 11.6% risk compared to Caucasian men at 7.4%. The risk difference is 4.1% (95% CI = 3.4, 4.9) p = 0.000. The RR is 1.56 (95% CI = 1.43, 1.70). In contrast, risk difference and risk ratio of IHD was not significant between AA and Caucasian groups. ADT exposure increases the risk of NODM in men with PCa, especially among AA men compared with Caucasian men. Men receiving ADT should be monitored routinely for signs and symptoms of metabolic syndrome and diabetes. Targeted close monitoring of AA men on ADT would be critical to prevent and treat metabolic complications with potential of reducing disparities in PCa morbidity.