ObjectivesBody size is postulated to modulate type 1 diabetes as either a trigger of islet autoimmunity or an accelerator to clinical onset after seroconversion. As overweight and obesity continue to rise among children, the aim of this study was to determine whether human leukocyte antigen DQ (HLA-DQ) genotypes may be related to body size among children genetically at risk for type 1 diabetes.MethodsRepeated measures of weight and height were collected from 5 969 children 2-4 years of age enrolled in The Environmental Determinants of Diabetes in the Young prospective study. Overweight and obesity was determined by the International Obesity Task Force cutoff values that correspond to body mass index of 25 and 30 kg/m(2) at age 18.ResultsThe average BMI was comparable across specific HLA genotypes at every age point. The proportion of overweight was not different by HLA, but percent obesity varied by age with a decreasing trend among DQ2/8 carriers (p for trend=0.0315). A multivariable regression model suggested DQ2/2 was associated with higher obesity risk at age four (OR, 2.41; 95% CI, 1.21-4.80) after adjusting for the development of islet autoantibody and/or type 1 diabetes.ConclusionsThe HLA-DQ2/2 genotype may predispose to obesity among 2-4 year old children with genetic risk for type 1 diabetes.