People who have recently quit smoking are more likely than habitual smokers to be diagnosed with type 2 diabetes — but quitting still lowers the risk of death from all chronic diseases.
In an analysis of three US study populations, Qi Sun at the Harvard T.H. Chan School of Public Health in Boston, Massachusetts, and his colleagues found that weight gain among recent quitters — defined as those who had abstained for 2–6 years — explained 68% of their increased risk of diabetes. Risk of developing the disease peaked 5–7 years after people stopped smoking, and then gradually fell.
In a separate study, Aidin Rawshani at the University of Gothenburg in Sweden and his colleagues assessed a cohort of about 271,000 people, and found that the greatest predictor of death among people with type 2 diabetes was smoking. People with diabetes had only a marginally higher risk of death than the general population, if they did not smoke and maintained four health indicators — blood pressure, blood sugar, cholesterol and urine concentrations of a protein called albumin — within ranges recommended by medical experts.