To solve the problem, we did a subgroup analysis to decrease the heterogeneity. Finally, some BAY 43-9006 studies included were population-based and did not specify the type of diabetes. We could not do a subgroup analysis according to type of diabetes. However, over 90% of individuals with diabetes in the general population have type 2 diabetes, so it would have little impact on pooled ORs. In conclusion, based on the results of this meta-analysis, metformin use appeared to be associated with a lower risk of lung cancer in diabetic patients, but the association disappeared when the analysis was restricted to the studies adjusted for Rapamycin smoking. Insulin use increased lung cancer risk, while sulfonylureas and TZDs did not significantly have an association with lung cancer risk. However, this observation needs further investigation before the findings can be translated to clinical practice. A definitive, randomised trial is needed to rigorously assess the effects of glucose-lowering drugs on lung cancer incidence in diabetic patients. The toxin elimination inside the peritrophic membrane could be due to rapid excretion, as occurs in M. unipuncta larvae or to a high rate of degradation inside this space. Recently Gonzalez-Cabrera et al indicated that the low levels of proteolytic enzymes involved in Cry toxin activation could be another reason for the low susceptibility of M. unipuncta to the Bt toxin. Insects possess three enzyme systems providing metabolic resistance to toxins: esterases, cytochrome P450 monooxygenases and glutathione-S-transferases. P450s are a multigenic superfamily of enzymes that are found in the biosynthetic pathways of ecdysteroids and juvenile hormones and may be the greatest detoxification mechanism available to insects when they are exposed to a foreign agent. Several authors have published excellent reviews of the roles played by these enzymes in insects, including growth, development, feeding, resistance to pesticides and tolerance to plant toxins. When the resistance to insecticides is mediated by monooxygenases, it is usually due to increased detoxification or decreased activation of the xenobiotics through overexpression or induction of the P450 genes.