 Our main objective is to evaluate the effect of stimulated and calculated water intake per kg of patient weight on the state of hydration and renal function in a population of elderly individuals. It is also within the scope of this project to evaluate the presence of chronic dehydration in elderly patients as well as in a subgroup of diabetic patients, and to compare different methods of evaluation of renal function. Design: Clinical trial Randomized for the main objective and cross-sectional study for secondary objectives. 