Introduction. Alzheimer's disease is a multifactorial disease affecting approximately twenty million people worldwide. Numerous variables are associated with increased risk of developing this severe neurological disorder. Among the risk factors, diabetes mellitus, and the ε4 isoform of the APOE gene have been amply demonstrated as increasing the risk of developing this disease.Objective. To determine if a correlation exists between APOE genotype, diabetes mellitus and Alzheimer's disease.Materials and methods. Clinical studies were carried out by surveying the clinical histories in a group of patients in the province of Antioquia, Colombia. Forty-three Alzheimer's patients were compared with 43 control subjects, paired by age and gender. Commercially available methods were used to determine whether the patients had diabetes, and restriction enzyme-based genotyping was used to determine the APOE genotypes.Results. The most common non-neurological comorbidities were: arterial hypertension, acute myocardial infarction, chronic obstructive pulmonary disease and hypothyroidism. From the many variables investigated, two were conclusive: (1) the presence of Alzheimer's disease was higher in patients with diabetes mellitus, and (2) no correlation between late-onset sporadic Alzheimer's disease and APOE was found in the target population.Conclusions. To detect any association with the APOE genotype, a study involving much a larger population samples must be undertaken.