Abstract INTRODUCTION Diabetic patients are at higher risk of developing malignancies. Studies have however suggested a contrasting data, indicating lower risk of prostate cancer in type 2 diabetics. Studies in some parts of the world showed lower PSA levels in diabetic patients, but yet to be verified in African living in Africa. AIM The aim was to determine the levels of PSA in Diabetic and Non-diabetic men in Maiduguri-Nigeria and to ascertain similar lower values in African living in Africa. MATERIALS AND METHODS This was a hospital based case-control study that included a total of 132 participants whose ages were from 40 years and above and voluntarily consented to be part of this study. Ethical clearance was obtained from Ethics and Research Committee of the University of Maiduguri Teaching Hospital, structured questionnaire was self-administered. One hundred and four (104) were confirmed type 2 DM male attending Metabolic Clinic University of Maiduguri Teaching Hospital and twenty eight (28) non-diabetic men, who had no history of hypertension, not using antihypertensives or steroid drugs, no history of cardiovascular diseases, not using anti-lipid drugs; not having cancer; non-smokers and non-alcoholic consented and served as control. Data on family history of DM, duration of the disease, hypertension and social lifestyle recorded for diabetic patients. Weight, height and BMI were calculated, Blood pressure, fasting glucose and serum for PSA were determined. RESULTS The mean ages of diabetic and non- diabetic men were 53.3 ± 11.8 and 53.9 ± 6.1 years, respectively. The mean total serum PSA was significantly lower in diabetic compared to non-diabetic (0.72 ± 0.09 ng/ml vs. 2.50 ± 0.44 ng/ml, respectively, p = 0.000). The mean fasting glucose was significantly higher among diabetic compared to non-diabetic p = 0.006). Diabetics were grouped into 5 according to their age (40 -49, 50-59, 60-69,70-79, ≥ 80). The age 70-79 years has the highest mean PSA level than all other groups (1.19 ± 0.45ng/ml), while age group ≥ 80 years has the least PSA value of (0.15 ± 0.05ng/ml). The mean fasting glucose is lowest in age group of ≥ 80years and highest in age groups of 50-59 and 40-49years (7.78 ± 0.68 and 7.56 ± 0.63mmol/L) respectively. The treatment modality was grouped into five; insulin 5(4.8%), oral 73(70.2%), oral and insulin 8(7.7%) and diet 18 (13.6%). Oral and insulin treatment has higher level of PSA (1.29 ±1.03 ng/ml) compared to all the other groups. The PSA levels were grouped based on the duration of diagnosis of DM (0-5, 6-10, 11-15, 16-20 and ≥ 21years) and 11-15 years duration have high levels of PSA than the other group. There was significant Pearson’s Correlation between PSA and age, systolic and diastolic (p=0.000, p=0.002 and p=0.006) respectively. CONCLUSION serum PSA level is significantly lower in type 2 diabetics than in non-diabetics in this study. This study and other findings recommend establishment of separate reference interval for Type 2 diabetic men for appropriate evaluation of their prostatic diseases using the PSA Citation Format: Rebecca Mtaku Gali, Dahiru Saleh Mshelia, Jessy Thomas Medugu, Musa Dungus, Hassan Dogo, Haruna Asura Nggada, Bata Mtaku Gali, Mwajim Bukar, Ahmad Gadam Ibrahim, Galadima Gadzama, Abubakar Farate. Low levels of PSA in diabetic Nigerians: A call for a separate reference range for prostate cancer screening among type-2 diabetics? [abstract]. In: Proceedings of the AACR Virtual Conference: Thirteenth AACR Conference on the Science of Cancer Health Disparities in Racial/Ethnic Minorities and the Medically Underserved; 2020 Oct 2-4. Philadelphia (PA): AACR; Cancer Epidemiol Biomarkers Prev 2020;29(12 Suppl):Abstract nr PO-088.