Baseline visit Activities to be carried out during the baseline visit are detailed in the Appendix A. Inclusion/exclusion criteria will be reviewed once again. At the baseline visit, participants will be instructed on how to prepare to stop smoking and to set a target quit date (TQD), which will be planned to coincide with the Week 1 visit. Also at the baseline visit, each participant will be randomly assigned to either varenicline 1 mg BID + counseling or matched placebo + counseling. Qualified site personnel will dispense the study drug and provide dosing instructions. The participants will be provided approximately. 10 minutes of counseling, in accordance with Agency for Healthcare Research and Quality (AHRQ) guidelines. Diabetic smokers will be subjected to their usual care throughout the study.