The incidence of type 2 diabetes mellitus (DM2) in children has increased worldwide and is commonly associated with overweight. Forty-four children with DM2 were studied by clinical histories, anthropometric measurements, and biochemical analysis. Homeostasis model assessment (HOMA-IR) and quantitative insulin sensitivity check index (QUICKI) were determined to evaluate insulin resistance. Only five patients presented normal body mass index (BMI); the remainder were overweight, and 76% had acanthosis nigricans. Laboratory results yielded hyperglycemia, elevated glycosylated hemoglobin, insulin and C-peptide. Elevated HOMA-IR and decreased QUICKI values suggest insulin resistance. No significant difference was found between sexes, although overweight in girls had more influence over blood pressure and lipid levels (p