Acute effects of nicotine on serum glucose, insulin, growth hormone, and cortisol in healthy smokers

Cigarette smoking impairs glucose tolerance and alters serum levels of hormones involved in glucose metabolism, but the role of nicotine in such hormonal alterations is not well understood. In order to isolate the effects of transdermal nicotine on serum glucose, insulin, growth hormone, and cortisol in smokers, we conducted a randomized double-blind placebo-controlled cross-over study involving 34 healthy volunteer smokers between 18 and 55 years of age. Administration of a 14-mg transclermal nicotine patch resulted in nonsignificantly lowered fasting quantitative insulin-sensitivity index (P =.11) and a nonsignificant 9.3-mg/dL mean increase in serum glucose levels during a 75-g oral glucose tolerance test (OGTT) at time 60 minutes (P =.12). There were no substantial differences between groups in the areas under the curve (AUCs) for glucose (P =.33) or insulin (P =.79) during the OGTT. Levels of insulin and cortisol also were not significantly altered by nicotine. A secondary finding observed in the overall study group (primarily in females) was that nicotine caused a 29% median decrease in serum growth hormone (P =.02). We conclude that nicotine patches may lead to mild hyperglycemia and lowered insulin sensitivity. Further research is needed to determine the clinical implications of the unexpected finding that nicotine decreased growth hormone levels in female smokers. (C) 2004 Elsevier Inc. All rights reserved.