Diabetes mellitus is an endocrine disorder that is debilitating and requires lifestyle modification for effective control. Depression is more prevalent among persons with diabetes mellitus compared to the general healthy population. Adverse childhood experiences have been associated with a variety of chronic medical illnesses and mental health problems including Diabetes and depression in adult life. Aims This study was aimed at assessing the associations between adverse childhood experiences (ACE) and the onset of Diabetes and Depression, among stable out-patients attending the Diabetic clinic of Federal Medical Center (FMC) Asaba, Delta state. Methods Three hundred patients attending the Diabetic clinic at the Federal Medical center, Asaba were studied. In addition to socio-demographic questionnaire, composite international diagnostic interview (CIDI) Depression module was used to diagnose Depression. The Hamilton Depression Rating Scale (HDRS) was used to asses Depression symptom severity, while the ACE questionnaire assessed adverse childhood experiences. Results The lifetime prevalence of Depression was 33.3% while the prevalence of current Depression was 17.7%. The prevalence of ACE was very high with rates of 74.3% found for those who had experienced at least one ACE. Having experienced ACE at all was significantly associated with both life time and current Depression. The study also revealed that ACE and Depression shared a common variance of up to 30% which is very significant. Conclusion Adverse childhood experiences were more likely to have significant associations with the onset of depression later in adulthood. Physicians need to pay more attention to co- morbidity of Depression among patients with Diabetes, as it has implications for service utilization and treatment outcomes.