The aim of this study is to analyze the potential impact of factors (clinical and demographic variables and comorbidities) associated with Diabetes Mellitus (DM) on certain mental processes related to cognitive impairment, with special attention to the analysis of parameters that define processing speed and executive function. Neuropsychological examination of elderly Spanish patients (N = 59, 33 females, M age 70.98 years) diagnosed with DM, in addition to application of an ad hoc questionnaire to collect information on comorbidities and other relevant demographic variables. Based on a cross-sectional design, correlational analysis was carried out. Cognitive performance showed an inverse relationship to age and cardiopathology while years of schooling and regular physical activity appeared as neuroprotective factors. DM is an illness which, linked to other variables, can be regarded as a risk factor for the development of cognitive impairment. Certain factors (physical activity and cognitive stimulation) have the potential to mitigate this tendency. There is a need to further our understanding of the neurobiological mechanisms involved.