Background

The risk of some forms of cancer has been found to be higher in patients with diabetes mellitus (DM) than in the general population. The aim of this study was to examine, with sufficient statistical power, the association between DM and lung cancer and the impact of antidiabetes drugs on lung cancer risk in Taiwan.

Materials and Methods

From a randomly selected data set of 1 million National Health Insurance (NHI) claims in Taiwan from 2000-2005, 19,624 cases (patients ≥ 20 years of age) of newly diagnosed DM were identified. From the same data set, 78,496 enrollees with no record of DM were selected as controls and were matched in sex and age to the first group. The incidence of newly diagnosed lung cancer was compared between patients with DM and controls for a period of 9 years (2000-2008).

Results

The multivariate Cox model analysis showed a slightly increased hazard ratio (HR) of 1.05 of lung cancer in patients with DM, but the association was not statistically significant. However the use of antidiabetes drugs, such as metformin, thiazolidinediones, or alpha-glucosidase inhibitors, correlates with a decreased lung cancer risk of 39%-45%. A significant association was found between lung cancer risk and male sex (HR, 2.23), pulmonary tuberculosis (HR, 1.60), chronic obstructive pulmonary disease (HR, 1.21), and age (HR, 1.07).

Conclusion

Patients with DM are not at increased risk for the development of lung cancer, but the use of antidiabetes drugs would considerably decrease the risk. In this cohort, male sex, age, pulmonary tuberculosis, and chronic obstructive pulmonary disease were all associated with an increased risk of lung cancer, consistent with findings in the literature and indicative of the validity of our study.