To identify risk factors associated with the development of diabetic ketoacidosis (DKA) in new-onset type 1 diabetes mellitus, a retrospective chart review of 139 new onset type 1 diabetes patients from 1995 to 1998 was conducted. Categorical data were examined with contingency table analysis. Age range was 0.5 to 18 years. Overall, 38% of the patients presented in DKA. Sixty-two percent of the patients with either Medicaid or no insurance presented in DKA compared to 34% of the patients with private insurance, odds ratio 3.17 (92% CI 1.2-8.3) p = 0.03. Sixty-eight percent of patients in whom the diagnosis was missed (n = 25) presented in DKA (mean age, 5.4 +/- 4.4 years) compared to 32% in whom the diagnosis was not missed (mean age, 8.8 +/- 4.0 years) odds ratio 4.6 (95% CI 1.9-11.7), p = 0.0012; age p = 0.00019. Lack of private insurance, although a risk factor for the development of DKA, did not increase the likelihood of a missed diagnosis. Lack of private insurance (a proxy for socioeconomic status) and young age are apparent risk factors for the development of ketoacidosis. Misdiagnosis by the physician at initial patient encounter is especially prevalent in the young child but not related to insurance. Both increased public awareness and greater medical alertness are necessary to reduce the high rates of DKA in new-onset type 1 diabetic children.