Smoking and lipid-related indices in patients with diabetes mellitus

Lipid-related indices, including the ratio of LDL cholesterol to HDL cholesterol, the ratio of triglycerides to HDL cholesterol and lipid accumulation product, are known to be good discriminators for cardiovascular disease. The aim of this study was to clarify the relationships between smoking and the lipid indices in patients with diabetes.

Subjects were those who had been diagnosed as having diabetes mellitus at annual health check-ups at their places of work (n = 2563). The subjects were divided into three groups of non-smokers, light smokers (≤ 20 cigarettes/day) and heavy smokers (> 20 cigarettes/day). The relationships between smoking and the lipid indices were investigated.

Both in all subjects and in the subjects without a habit of alcohol drinking, the LDL cholesterol:HDL cholesterol ratio and the log-transformed triglyerides:HDL cholesterol ratio tended to be higher with an increase in the amount of smoking, and the log-transformed lipid accumulation product was significantly higher in heavy smokers than in non-smokers. In the non-alcohol drinking subjects, the odds ratios of heavy smokers vs. non-smokers for high LDL cholesterol:HDL cholesterol ratio [2.32 (95% CI 1.40-3.84)], for high triglycerides:HDL cholesterol ratio [1.69 (95% CI 1.06-2.69)] and for high lipid accumulation product [1.65 (95% CI 1.02-2.67)] were significantly higher than a reference level of 1.00. The associations between smoking and the lipid indices were weaker in alcohol drinkers than in non-drinkers.

In patients with diabetes, the levels of lipid-related indices were higher in smokers than in non-smokers, and cardiometabolic disorders, reflected by high lipid indices, are thought to be involved in the proneness of smokers to develop atherosclerotic cardiovascular disease.