Background: Nutrition and dietary habits is one of the determinant factor on glycemic control of diabetes mellitus. This study aims to investigate the association between type 1 diabetes mellitus (T1DM) and diet in the first two years of life as well as a select group of demographic variables. Methods: This case-control study was conducted on 76 children with T1DM and 209 non-diabetic children selected through convenience sampling from the population of people visiting the community health centers of the city of Jahrom, Iran. The required data were collected by a questionnaire of diet and demographic information completed by the mothers of the children. The data were analyzed using logistic regression and adjusted odds ratio. Results: Finally, the results of multiple backward logistic regression showed that the studied factors had a significant association with T1DM (P < 0.05), including body mass index (BMI) less than 18 kg/m2 for mothers before pregnancy (OR: 4.4, 95% CI: 1.61 to 11.97), mothers without a history of diabetes (OR: 0.02, 95% CI: 0.001 to 0.60), mother’s weight before pregnancy (OR: 0.88, 95% CI: 0.84 to 0.91), mother’s excess weight during pregnancy (OR: 0.83, 95% CI: 0.75 to 0.93), exclusive breastfeeding for more than six months (OR: 0.19, 95% CI: 0.03 to 0.96), low weight gain in the first two years of life (OR: 6.98, 95% CI: 2.16 to 22.5), and the breastfeeding less than 12 months (OR: 10.52, 95% CI: 1.62 to 66.64). Conclusion: BMI less than 18 kg/m2 for mothers before pregnancy, low weight gain in the first two years of life, and breastfeeding less than 12 months increased the risk of developing T1DM in children.