 Single-center, randomized, double-blind, placebo-controlled, crossover, safety, activity, and pharmacokinetic PK study of 2.0 g of SRT2104 administered orally once daily for 28 consecutive days to two different populations: type 2 diabetic T2D subjects on an existing, stable, hypoglycemic regimen and otherwise healthy cigarette smokers 10cigarettesday for at least 1 year. Approximately 24 subjects with T2D and 24 otherwise healthy cigarette smokers, aged 18-60 years, who fulfill the inclusionexclusion criteria, will be enrolled in this study to ensure at least 20 evaluable subjects per population are enrolled. Subjects will be evenly stratified and randomized to receive SRT2104 2.0 gday or placebo once daily for 28 days. After 28 days, subjects will cross over to receive the other test article for another 28 days of dosing, bringing the total dosing period to 56 days. 