Common Variation in the FTO Gene Alters Diabetes-Related Metabolic Traits to the Extent Expected Given Its Effect on BMI

OBJECTIVE—Common variation in the FTO gene is associated with BMI and type 2 diabetes. Increased BMI is associated with diabetes risk factors, including raised insulin, glucose, and triglycerides. We aimed to test whether FTO genotype is associ-ated with variation in these metabolic traits. RESEARCH DESIGN AND METHODS—We tested the asso-ciation between FTO genotype and 10 metabolic traits using data from 17,037 white European individuals. We compared the observed effect of FTO genotype on each trait to that expected given the FTO-BMI and BMI-trait associations. RESULTS—Each copy of the FTO rs9939609 A allele was associated with higher fasting insulin (0.039 SD [95 % CI 0.013– 0.064]; P 0.003), glucose (0.024 [0.001–0.048]; P 0.044), and triglycerides (0.028 [0.003–0.052]; P 0.025) and lower HDL cholesterol (0.032 [0.008–0.057]; P 0.009). There was n