THE INSULIN-RESISTANCE SYNDROME AND POSTPRANDIAL LIPID INTOLERANCE INSMOKERS

Background: The effects of cigarette smoking on insulin resistance, po stprandial lipemia following a mixed meal, lipoproteins and other aspe cts of the insulin resistance syndrome (IRS) were investigated in heal thy middle-aged men. Methods: 36 smoking and 25 age- and body mass ind ex (BMI)-matched non-smoking men participated. They were non-obese (BM I < 27), healthy and without any medication. The smokers had been smok ing more than 10 cigarettes per day for more than 20 years; the non-sm okers had never been habitual smokers. Body composition and several me tabolic and cardiovascular risk factors were studied, including the pr evalence of small dense LDL-particles, lipoprotein and hepatic lipase activity and triglyceride levels after a mixed lest meal. For determin ation of degree of insulin sensitivity the euglycemic hyperinsulinemic clamp technique was used. Results: The smokers had lower HDL-choleste rol and lipoprotein A-I levels but higher fasting triglycerides, as we ll as an increased proportion of small dense LDL-particles and higher postheparin hepatic lipase activity. They also had higher levels of fi brinogen, plasminogen activator inhibitor 1 (PAI-1) activity and fasti ng and steady-state C-peptide levels during the clamp. The smokers wer e insulin resistant and lipid intolerant with an impaired triglyceride clearance after a mixed test meal. This lipid intolerance was not mir rored by fasting hypertriglyceridemia. Conclusions: This study, using the euglycemic hyperinsulinemic clamp technique, shows that smokers ar e both insulin resistant and lipid intolerant. The postprandial lipid intolerance is also seen in individuals with normal fasting triglyceri de levels and is related to an increased prevalence of atherogenic sma ll dense LDL. IRS is likely to be an important reason for the increase d cardiovascular morbidity in smokers. (C) 1997 Elsevier Science Irela nd Ltd.