Aims/hypothesis Surveys in northern Ethiopia have demonstrated that apparent type 1 diabetes occurs more frequently than elsewhere in Africa and, indeed, in other parts of the world. We therefore investigated in detail a cohort of diabetic patients from this region to clarify the nature of this type of diabetes. Methods All patients attending the diabetic clinic at Mekelle Hospital in the Tigray region of northern Ethiopia were investigated over a 6 week period. Clinical, demographic and anthropometric data were collected, as well as measurements of HbA 1c , fasting lipid profile, fasting serum Cpeptide and serum markers of beta cell autoimmunity, i.e. islet antigen-2 and GAD antibodies (GADA). Results Of 105 patients seen, 69 (66%) were on insulin treatment and had been from or close to diagnosis. Their median age and diabetes duration were 30 and 5 years, respectively, with a male excess of 2:1. Median BMI was 20.6 kg/m 2 . Despite these clinical characteristics suggestive of type 1 diabetes, only 42 of 69 (61%) patients were Cpeptide-negative and 35% GADA-positive. Overall, 38 (36%) of the total group (n=105) had immunological or C-peptide characteristics inconsistent with typical type 1 or type 2 diabetes. The clinical characteristics, local prevalence of undernutrition, and GADA and C-peptide heterogeneity suggest a malnutrition-related form of diabetes. Conclusions/interpretation Not all patients in northern Ethiopia with apparent type 1 diabetes appear to have the form of disease seen in Europids; their disease may, in fact, be related to malnutrition.