Among the population of Nauru there is a high prevalence of diabetes with onset in early adult life. To ascertain whether autoimmunity to islet cell antigens contributes to this diabetes, a population survey of serum autoantibodies was performed. Subjects were grouped into euglycaemic control subjects, those with impaired glucose tolerance, and those with diabetes subdivided according to duration of disease. No subject was positive by immunofluorescence for islet cell autoantibodies. Various other autoantibodies to nuclear, thyroid and gastric autoantigens were detectable, at comparable frequencies in the three groups. This population study on Nauruan subjects selected to include those in the early phases of disease negates a contribution from islet cell autoimmunity, and thus supports the concept that the disease is the Type 2 (non-insulin-dependent) type.