Background: Among older people, physical exercise improves cognitive function, aerobic fitness, and thus functional independence. Aim: To determine the effects of a walking training program on aerobic fitness and cognitive function in older women with type 2 diabetes mellitus. Material and Methods: An experimental study was carried out in 76 women with type 2 diabetes mellitus aged between 64 and 78 years. Thirty-eight women in the exercise group (EG) participated in a controlled walking program 3 times a week for 48 sessions (60min /day) and 38 women in the control group (CG) were not trained. Weight, height, body mass index (BMI), estimated maximal oxygen uptake (VO2max), and cognitive function using the Minimental test were evaluated at baseline and the end of the intervention. Results: The Minimental test improved significantly in the exercise group and did not change in the control group. Estimated VO- 2max improved in women aged between 69 and 78 years. The distance walked in 6 minutes increased in all women of the experimental group. No changes in these parameters were observed in the control group. Conclusions: A structured walking program improved cognitive function, estimated aerobic capacity, and walking distance in these diabetic women.