Introduction: Childhood obesity represents a serious public health problem in Mexico, related to the increase in the prevalence of diabetes mellitus 2 in children. Objective: To identify the prevalence of prediabetes by means of fasting glucose measurements and glycosylated hemoglobin in children between 5 and 16 years of age, with obesity or overweight from the pediatric consultation of a second level hospital. Materials and methods: Observational, analytical, comparative, prospective and transversal study. Non-probabilistic sampling, 165 patients between 5 and 15 years old 11 months of age, overweight or obese, fasting plasma glucose and glycosylated hemoglobin were determined. Chi Square statistical analysis to measure association between obesity, overweight, gender and age with abnormal serum glucose levels. Results: No gender predominance. 15% were overweight and 85% were obese. The prevalence of fasting hyperglycemia was 7%, in the elevation of glycosylated hemoglobin was 4%. Both results predominated in adolescent females. Statistically significant association between age and elevation of glycosylated hemoglobin. Conclusion: It was possible to establish the relationship between adolescence and elevation of glycosylated hemoglobin by means of statistical tests. The relation between obesity, gender and elevation of serum glucose was observed but it was not possible to prove it by means of statistical methods.