Aims/hypothesis: There is evidence of overlap between susceptibility loci for type 2 diabetes and obesity. The aim of this study is to explore the association between the established type 2 diabetes locus KCNQ1 and obesity in Han Chinese.
Methods: We recruited 6,667 and 6,606 diabetic case-control samples from Shanghai and Hong Kong, respectively. Of the samples, 7.5% and 6.3% were excluded because of genotyping failure or data missing in the association analyses of rs2237892 and rs2237895 with obesity/BMI, respectively.
Results: We found that rs2237892 was associated with lower BMI and lower incidence of overweight/obesity in diabetic patients from Hong Kong (BMI, β = -0.0060 per diabetes risk C allele for log(10)BMI [95% CI -0.0088, -0.0032; p = 2.83 × 10(-5)]; overweight/obesity, OR 0.880 for C allele [95% CI 0.807, 0.960; p = 0.004]) and in the meta-analysis of cases from the two regions (BMI, combined β = -0.0048 per C allele for log(10)BMI [95% CI -0.0070, -0.0026; p = 2.20 × 10(-5)]; overweight/obesity, combined OR 0.890 for C allele [95% CI 0.830, 0.955; p = 0.001]). rs2237895 was also related to decreased BMI (combined β = -0.0042 per diabetes risk C allele for log(10)BMI [95% CI -0.0062, -0.0022; p = 4.30 × 10(-5)]). A significant association with waist circumference was detected for rs2237892 in the pooled analyses (β = -0.0026 per C allele for log(10)[waist circumference] [95% CI -0.0045, -0.0007; p = 0.007]). However, neither an association with the risk of being overweight or obese nor associations with quantitive traits were detected for rs2237892 or rs2237895 in controls.
Conclusion: Our findings indicate that KCNQ1 is associated with obesity in Chinese patients with type 2 diabetes.