Type I diabetes has a very low incidence in China, although the reasons for this have not been well studied. In order to consider some environmental factors associated with type 1 diabetes, a subset of registry cases (N=292) from China and sex, age, ethnic, and geographically matched controls (N=496) without diabetes were studied. Local centers throughout mainland China collected questionnaire data regarding medical history, demographics, and environmental exposure, and biologic samples for genetic, immunologic, and C-peptide measures from cases and controls. The cases recruited for study were shown to be representative of the entire Chinese registry population. Type 1 diabetes cases were 47% male, had a mean age of onset of 9.6 + 3.5 years, and had a mean age of clinic visit of 14.2 + 4.5 years. Ethnic origin of cases was 97% Han. 1.4% Mongol, 1.0% Hui, and 0.7% Man. Based on fasting C-peptide tests and evaluation of immunologic markers (GAD and IA-2) of type 1 diabetes, our sample of registry cases were determined to have autoimmune type 1 diabetes. Socioeconomic group and birth cohort were strongly related to food consumption in infancy for both cases and controls. SES was lower in cases compared to controls (38% low. 54% medium. 8% high vs. 26% low, 66% medium, 8% high; p<0.01). In multivariate logistic regression analyses which controlled for SES, birth year, and breastfeeding status, soy formula consumption from 6-12 months of age was a risk factor for type 1 diabetes (OR=l.44; 95%CI: 1.01-2.05; p<0.05) and steamed bread consumption at 4-6 (OR=0.65; 95%CI: 0.45-0.94; p<0.05) and 6-12 months of age (OR=0.54; 95%CI: 0.38-0.77; p<0.001), fish consumption at 6-12 months of age (OR=0.63; 95%CI: 0.42-0.95; p<0.05), and noodle consumption at 6-12 months of age (OR=0.60; 95%CI: 0.39-0.91; p<0.05) were protective for type 1 diabetes. More cases were introduced to solid food by 3 months of age than controls (21% vs. 14%; p<0.05). Infant diet may play a more important role etiology than previously considered. Differences in genetics and environmental risk factors, such as nutrition, may explain the lower incidence found in China compared with other populations.