For 51 (5%) of the 1052 Maori patients registered with the Northland New Zealand (NZ) Diabetes Service, an initial diagnosis of diabetes was made before they had reached 30 years of age. We reviewed epidemiological and clinical data of this patient group. A total of 28 patients (55%) have type 2 diabetes, 18 (35%) have type 1 diabetes and for five patients, we were unable to determine the type of diabetes. The majority have positive family histories of diabetes (83%). The average age at diagnosis was 12.4 years for type 1 and 19.1 years for type 2 diabetes. Mean duration of diabetes and mean current HbA1c were not statistically different between the two groups, yet microalbuminuria or nephropathy was present in 62% of type 2 patients, but only 18% of the type 1 group. These statistics show that a significant number of Northland NZ Maori develop type 2 diabetes at an earlier age than expected and have a high incidence of renal complications. These findings contrast with previous New Zealand studies on the incidence of diabetes in young Maori, but are similar to those of recent overseas studies of ethnic groups with a high incidence of diabetes.