Background: Cognitive impairment occurs in both schizophrenia (SZ) and diabetes mellitus, in addition, people with SZ are more likely to develop diabetes than those without SZ. Objective: This study was planned to determine whether SZ patients with diabetes have an increased risk of cognitive impairment than SZ without diabetes or diabetes only. Subjects & Methods: The study included 120 subjects, 30 of them were known patients with SZ (Group I), 30 with type 2 diabetes mellitus (T2DM) (group II), 30 of them had SZ with diabetes (Group III) as well as 30 healthy subjects served as control group (Group IV). All subjects were subjected to complete clinical examination, including body mass index [BMI] and waist circumference, in addition to investigations including fasting blood glucose, lipid profile and routine laboratory investigations and assessment of cognitive functions using RBANS [Repeatable Battery for the Assessment of Neuropsychological Status]. Results: SZ with diabetes showed higher fasting blood glucose and triglyceride levels than SZ without diabetes (both P < 0.05). No significant differences between SZ with and without diabetes in duration of illness, antipsychotic types, duration of current antipsychotic treatment (all P > 0.05). Compared to healthy controls, all patients groups had significantly decreased total and five index RBANS scores [the repeatable pattery for assessment of neuropsychological status] (all P < 0.01 – P < 0.001), except for the visuospatial/ constructional index. SZ with diabetes performed worse than SZ without diabetes in immediate memory (P > 0.01) and total RBANS scores (P < 0.05) and showed a trend for decreased attention (P = 0.052) and visuospatial/constructional capacity (P = 0.63). SZ with diabetes performed worse than diabetes only in immediate memory (P < 0.001) and attention (P < 0.05) and showed a trend for decreased total RBANS scores (P = 0.069). Conclusion and Recommendations: SZ with Co-morbid diabetes showed more impairment than SZ without diabetes or diabetes only especially in immediate memory & attention. Thus, diabetes prevention and control should be targeted in patients with SZ.