Insulin use was associated with a statistically significant 22% increase in lung cancer risk in patients with diabetes on meta-analysis of eight observational studies (OR 1.23 95% CI 1.10 to 1.35 P = 0.096 for heterogeneity) (Figure 2d) [9], [10], [14], [16], [17], [33], [35], [37]. This evidence concerns the gene INS and diabetes mellitus.