Smoking is one of the main risk factors for cardiovascular disease (CVD). The mechanism(s) for the effects of smoking on CVD are not clearly understood; however, a number of atherogenic characteristics such as insulin resistance have been reported.

We aim to investigate the effects of cigarette smoking on insulin resistance and to determine the correlation between this parameter with smoking status characteristics.

This study was conducted on 138 nonsmokers and 162 smokers aged respectively 35.55±16.03 and 38.47±21.91 years. All subjects are not diabetics. Fasting glucose was determined by enzymatic methods and insulin by chemiluminescence method. Insulin resistance (IR) was estimated using the Homeostasis Model of Assessment equation: HOMA-IR = [fasting insulin (mU/L) × fasting glucose (mmol/L)] /22.5. IR was defined as the upper quartile of HOMA-IR. Values above 2.5 were taken as abnormal and reflect insulin resistance.

Compared to non-smokers, smokers had significantly higher levels of fasting glucose, fasting insulin and HOMA-IR index. A statistically significant association was noted between the smoking status parameters, including both the number of cigarettes smoked/day and the duration of smoking, and fasting insulin levels as well for HOMA-IR index. Among smokers, we noted a positive correlation between HOMA-IR index and both plasma thiocyanates and urinary cotinine.

The findings show that smokers have a high risk to developing an insulin resistant, hyperinsulinaemic, compared with a matched group of non-smokers, and may help to explain the high risk of cardiovascular diseases in smokers.