Diabetes mellitus has become a serious health concern in Kenya. The study sought to investigate the patients'' level of physical activity, their knowledge on exercise in managing diabetes, factors associated with the patients'' participation in physical activity (PA) and the relationship between the diabetics PA levels and their age, gender, duration of the condition, type of diabetes and knowledge on exercise. Testing of the hypotheses yielded conclusions that the patients'' age, type of diabetes, duration of diabetes and knowledge on exercise had significant relationships with the patients'' physical activity levels while gender had no significant relationship with the physical activity levels. Physical activity level, though seen as sufficient to a good percentage of diabetics, may not be sustainable. This is because physical activities changes at different seasons and state of diabetes control. This may deter the effectiveness of exercise therapy in this population. The diabetics also portrayed sufficient knowledge on exercise as taught at the clinic but lacked in fundamental instruction, supervision and specific exercise prescription resulting in difficulty and contraindications.