Alterations of glucose metabolism in diabetes have been suggested as promoting Helicobacter pylori colonization. We performed a cross-sectional sero-prevalence study of diabetic patients (insulin-dependent, or type 1, and non-insulin-dependent, or type 2, diabetes mellitus) with H. pylori and compared them with a control group. Consecutive diabetic outpatients aged 12 to 75 y and with disease duration of greater than 1 y were enrolled. Helicobacter pylori status was evaluated by using an enzyme-linked immunosorbent assay for anti-H. pylori immunoglobulin G. Demographic data were obtained from each individual, and socioeconomic class was assessed by occupation and education level. A total of 891 individuals participated (240 with type-2 diabetes, 145 with type-1 diabetes, and 506 control subjects). After controlling for age, there was no significant difference in the prevalence of H. pylori infection in any age group. In fact, the prevalence of H. pylori was numerically higher among children in the control group than among children with type-1 diabetes (25% versus 9%, respectively; P = 0.1). Previous associations of H. pylori and diabetes may have arisen from failure to consider socioeconomic status or age. Because childhood is the most common period for acquisition of H. pylori infection, the higher prevalence of infection among the normal children as opposed to those with type-1 diabetes confirms the lack of an association.