Objective: To investigate the acute effect of cigarette smoking on glucose tolerance, insulin sensitivity, serum lipids, blood pressure, and heart rate.
Research design and methods: This nonrandomized experimental control trial in a tertiary care center included 20 healthy chronic smokers and 20 age-, sex-, and BMI-matched healthy volunteers. Two oral glucose tolerance tests (OGTTs) were performed on each subject. Three cigarettes were smoked during the first 30 min in one of the tests. Serum glucose, insulin, and C-peptide levels were measured every 30 min; the area under the curve (AUC) and the insulin sensitivity index (ISI) were calculated; serum total cholesterol, LDL cholesterol, HDL cholesterol, and triglyceride levels were measured at 0 and 180 min; and blood pressure and heart rate were recorded every 5 min throughout 180 min.
Results: Smoking acutely impaired glucose tolerance: the AUC for glucose in smokers was 25.5 +/- 1.03 mmol/l (mean +/- SE) (95% CI 22.9-28) during the smoking OGTT and 21.8 +/- 0.85 mmol/l (CI 19.2-24.3) in the control OGTT (P < 0.01); in nonsmokers, it was 19.7 +/- 0.3 mmol/l (CI 18.8-20.5) in the smoking OGTT and 18.7 +/- 0.35 mmol/l (CI 17.8-19.5) in the control OGTT (P < 0.05). Smoking acutely increased serum insulin and C-peptide levels and decreased ISI only in smokers: ISI in smokers was 55 +/- 2.8 (CI 47.4-62.6) in the control OGTT and 43 +/- 2.7 (CI 35.4-50.6) in the smoking OGTT (P < 0.05). Smoking acutely caused a rise of serum total cholesterol levels in both groups and increased LDL cholesterol and triglyceride serum levels significantly only in smokers (P < 0.05). A significant rise of blood pressure and heart rate while smoking was present in all the subjects.
Conclusions: Smoking acutely impaired glucose tolerance and insulin sensitivity, enhanced serum cholesterol and triglyceride levels, and raised blood pressure and heart rate. These findings support the pathogenetic role of cigarette smoking on cardiovascular risk factors.