OBJECTIVE: To test whether immigrant versus nonimmigrant origin, among other factors, is associated with differences in glycemic control in diabetic children. RESEARCH DESIGN AND METHODS: A cross-sectional multicenter survey was performed in 165 French diabetic children aged 7–13 years and their parents. HbA1c was measured by high-performance liquid chromatography in a single laboratory (reference value: 5.1 ± 0.6%). Standardized questionnaires were used to evaluate cognitive, familial, and socioeconomic factors and adherence to diabetes regimen. RESULTS: The mother's place of birth was found to account for 6.6% of the HbA1c variance. Two groups of children were identified with French-speaking immigrant (n = 27) and native French mothers (n = 138) who had significantly different HbA1c values of 9.1 ± 8% vs. 8.1 ± 1.4%, respectively (P < 0.001). Adherence to diabetes treatment was significantly lower in immigrant mothers for diet and insulin changes (P < 0.01), as well as their level of diabetes knowledge (P < 0.01). This immigrant group had no significant differences in parents' socioeconomic status, educational background, family status, family functioning, diabetes education background, and social support compared with the native French mothers' group. CONCLUSIONS: Despite no differences in socioeconomic status, a group of children with less well-controlled diabetes was identified by the mother's place of birth. Cultural factors have a crucial importance in glycemic control in diabetic children and in parents' adherence to treatment and must be taken into account in the development of educational programs.