Additional research is needed to tease out the differences between the effects of nicotine and cigarettes on the endocrine system and to decipher the physiological and clinical relevance of these hormonal changes; this information is lacking in the current literature. In addition, the effects of second-hand smoke and of other forms of nicotine (nicotine replacement therapies such as gums and patches, as well as chewless tobacco, Hookah, and electronic cigarettes) on the endocrine and metabolic systems also need to be explored. Future studies should focus on providing useful information on the mechanisms of smoking-associated endocrine and metabolic diseases and give additional credence to smoking cessation.