A population survey in 1982 has confirmed that Nauruan adults suffer from an extremely high prevalence of Type 2 (noninsulin-dependent) diabetes mellitus. The crude population prevalence of Type 2 diabetes was 24%. Abnormal glucose tolerance (impaired glucose tolerance and diabetes) was present in over 40% of the adult population and exceeded 80% in both sexes after the age of 55 yr. Diabetic retinopathy was present in 24% of diabetic patients, confirming that this Micronesian population is susceptible to the microvascular consequences of hyperglycaemia. Subjects with impaired glucose tolerance had a prevalence of retinopathy three times that of normal subjects, though the difference did not reach statistical significance. Prevalence of retinopathy was substantially higher in diabetic patients than either normal subjects or those with impaired glucose tolerance.