All statistical analyses were undertaken using the SAS software (v9.1, SAS Institute, Cary, NC, USA). Haploview v4.0 (http://www.broad.mit.edu/mpg/haploview) was used to determine Hardy–Weinberg equilibrium (HWE). All genotypes fulfilled HWE expectations (P > 0.01). Generalized linear models were used to test genotype associations for continuous outcome traits (i.e. height, weight, BMI and DEXA measures of adiposity). Logistic regression was used to assess the association between each variant and obesity or type 2 diabetes as binary variables defined according to the definitions of the World Health Organization and ADA (13,14). All models were adjusted for age and sex and assumed an additive mode of inheritance. For anthropometric outcome variables, interaction tests were performed to determine whether the genetic effects differed by sex. This was achieved by fitting a term for genotype (0,1,2) × sex (0,1) to the regression models. For the models where obesity or type 2 diabetes were the outcomes, the area under the ROCAUC for each variant was calculated and compared with the ROCAUC derived from a model including all genotypes simultaneously. These analyses were performed using the methods described by DeLong et al. (17).
