Vitamin B12 deficiency is a common yet underdiagnosed condition in individuals with Type 2 Diabetes Mellitus (T2DM), especially those on long-term metformin therapy. This study aims to evaluate the prevalence and effects of vitamin B12 deficiency in a cohort of 100 T2DM patients. Data analysis revealed a significant correlation between B12 deficiency and neuropathy, fatigue, and other metabolic disturbances. These findings emphasize the need for regular monitoring of vitamin B12 levels in T2DM management.