Most insulin-requiring diabetes patients in Ethiopia have an atypical form of the disease, which resembles previous descriptions of malnutrition-related diabetes. As so little is known about its aetiology, we have carried out a case-control study to evaluate its social and nutritional determinants. Men and women with insulin-requiring diabetes (n=107), aged 18-40 years, were recruited in two centres, Gondar and Jimma, 750 km northwest and 330 km southwest of the capital, Addis Ababa, respectively. Controls of similar age and sex (n=110) were recruited from patients attending other hospital clinics. Diabetes was strongly associated with subsistence farming, odds ratio=3.5 (95% confidence interval: 1.5-7.8) and illiteracy/low levels of education, odds ratio=4.0 (2.0-8.0). Diabetes was also linked with a history of childhood malnutrition, odds ratio=5.5 (1.0-29.0) the mother's death during childhood, odds ratio=3.9 (1.0-14.8), and markers of poverty including poorer access to sanitation (P=0.004), clean water (P=0.009), greater overcrowding (P=0.04), increased distance from the clinic (P=0.01) and having fewer possessions (P=0.01). Compared with controls, people with diabetes had low mid upper arm circumference, body mass index (BMI) and fat/lean body mass (P<0.01). In addition, men with the disease tended to be shorter, were lighter (P=0.001), with reduced sitting height (P=0.015) and reduced biacromial (P=0.003) and bitrochanteric (P=0.008) diameters. Insulin-requiring diabetes in Ethiopia is strongly linked with poor education and markers of poverty. Men with the disease have associated disproportionate skeletal growth. These findings point towards a nutritional aetiology for this condition although the nature of the nutritional deficiency and its timing during growth and development remains obscure.