There was moderate evidence for heterogeneity across studies (I2=38.2%, p=0.12), mostly accounted for by Stranges et al. which reported a non-significant “protective” association of elevated PAI-1 with diabetes risk (removal of this study from the meta-analysis reduced the I2 statistic to 25% (p=0.24) without materially changing the pooled RR [1.74, 95% CI 1.37–2.22])27. This evidence concerns the gene SERPINE1 and diabetes mellitus.