Statistical power for fasting glucose and type 2 diabetes analyses in the combined UKADS/DGP study population.

RAF = risk (glucose-raising) allele frequency. Power was calculated using the South Asian RAF, the effect sizes reported in the MAGIC study [1], the sample sizes used in each analysis, an additive model and a significance level (α) of 0.05. For the type 2 diabetes analyses power calculations, a disease prevalence of 10% was assumed. For the fasting glucose analyses a population mean (SD) fasting glucose of 5.5 (0.6) mmol/l was used, as reported in Table 1.aIn the current study the GCK rs1799884 SNP was used as a proxy for the rs4607517 variant reported in MAGIC (r2 = 1.0 in CEU HapMap samples); the MAGIC RAF shown is for rs4607517.bFor the G6PC2 rs560887 SNP, the glucose-raising allele reduces the risk of type 2 diabetes (with nominal significance) in the MAGIC study. In this instance, to calculate power for the type 2 diabetes analysis the minor allele frequency (0.16) and the inverse of the odds ratio (OR; 1.03) was used.cThe RAF for the TCF7L2 rs7903146 SNP was not given in the MAGIC study; the RAF reported is for rs4506565 (r2 = 0.92 between the two variants in MAGIC).