Objective: The use of certain medications among diabetic patients put them at risk of developing bladder cancer. This study was done to examine the effects of metformin therapy on the bladder of diabetic patients and to assess the correlation between the effects of metformin and its duration of therapy. Methods: A total of 150 diabetic patients were sampled using a cross sectional study design. 10-15mls of random urine samples were collected into sterile containers over a period of five weeks. Smears were prepared, fixed and stained using Papanicolaou staining method and examined under the microscope for cytological studies. Results: The probability of developing bladder cancer among diabetic patients on metformin therapy is 0% among participants of all categories: 99 females and 51 males partook in this study.  Peak age group (35.33%) were between the ages of 51 to 60 years, least age group (4.67%) were 80 years and above. Traders of food items and used clothes constituted the peak occupational group of 27.52%, with fishermen  as least occupation group(0.67%), age group 61 to 70 had the highest duration of therapy of (15.8%), the least duration of (4.625%) was among age group 25 to 30 years, the group of 80years and above had a duration of (4.857%).  No inflammatory, degenerative, benign or malignant cells were observed among urine samples from diabetic patients on metformin. Conclusion: This study equips us with knowledge that metformin therapy has no direct influence on the development of cancer of the bladder among diabetic patients as observed through urine cytology. This is the first time such study is done in West Africa region. The clinical implication is that Metformin, the commonest prescribed oral hypoglycemic is safe when considering the carcinogenic effects of anti-diabetic drugs, unlike insulin and some other drugs which have carcinogenic potential.   Keywords: metformin; cancer; bladder; diabetes; therapy