Objectives: Diabetes mellitus is one of the most common chronic diseases in the general population. A study is made of the presence of caries in type 1 diabetic patients. The specific aim was to determine whether such patients present a greater incidence of dental caries than non-diabetic individuals. An evaluation was also made of the relationship of caries to salivary flow and to factors inherent to the disease such as the degree of metabolic control, the duration of diabetes, and the existence of chronic complications. Study design: The study comprised 90 type 1 diabetics between 18 and 50 years of age, and a group of non-diabetic controls matched for age and sex. Visual and tactile exploration of the dentition was carried out in all cases. Oral hygiene was rated based on the O?Leary plaque index, and basal (unstimulated) and stimulated salivary flow were evaluated in both groups. In the diabetic group, correlations were established with disease control based on the mean glycosylated hemoglobin (HbA1c) value corresponding to the two years prior to examination; evolution of the disease in years; and the existence of complications such as diabetic neuropathy or retinopathy. Results: Under similar conditions of oral hygiene and salivary flow, the diabetic group showed a higher incidence of caries than the control group (p<0.05). Likewise, on specifically analyzing the diabetic group, metabolic control of the disease, the duration of diabetes, and the existence of complications of the disease exerted an influence upon the development of dental caries. Conclusions: Qualitative salivary studies are advised to better account for this increased incidence of caries in the diabetic population.