The method to identify early the predisposition for Diabetes mellitus should be investigated, since the disease is a public health problem. Scholars of iridology claim that the Sign of Pancreas and the Cross of Andreas suggest predisposition to diabetes. Our objectives were to determine the prevalence of these signals in subjects with and without the disease and its heritability. Data collection occurred between February 2010 and June 2011. Participants 356 individuals older than 30 years treated at the Health Center School. Individuals with diabetes had a higher prevalence of signs studied iridology. The Student t test showed statistically significant differences in the prevalence of these signs between patients with and without diabetes and among individuals with and without family history of the disease. The Chi Square demonstrates that having both signals increase the chance of developing diabetes. The Pearson correlation coefficient shows a correlation between the signals studied with a family history of diabetes and the blood glucose alteration. We conclude that these signs suggest a predisposition to diabetes and that further studies are needed to assess the heritability.