Diverging sex-specific long-term effects of cigarette smoking on fasting insulin and glucose levels in non-diabetic people

ObjectivesWe determined in non-diabetic persons the associations of current smoking with future glucose and insulin concentrations.Design and methodsMiddle-aged non-diabetic adults (n = 1071) were studied in whom these values were measured at baseline and 5.2-years later.ResultsAge-adjusted fasting insulin concentrations in 137 smoking men remained lower than never smokers at both surveys. While age-adjusted fasting glucose values in male never smokers declined at follow-up (p = 0.037), they rose in male smokers. In 94 female smokers, age-adjusted fasting insulin values marginally declined, and fasting glucose was reduced (by 0.09 mmol/L, p = 0.055) during follow-up. In contrast in never-smoking women, insulin and glucose concentrations rose (p < 0.001 in both). Age-adjusted insulin levels in former smokers exhibited similar trends as never smokers. Trends were essentially unchanged when adjustment included body mass index. Current male smokers demonstrated evidence of reduced insulin sensitivity, female smokers of improved one, as assessed by QUICKI.ConclusionSmoking among Turks induces at long-term lower fasting insulin levels which represent improved insulin sensitivity in women, yet a reduced one in men.