Does Smoking Increase Risk for Diabetes?

New information suggests physiological changes in smokers may put them at risk for diabetes development…. 

The Surgeon General’s 50^th Anniversary report on smoking comes with new information which suggests that not only is smoking bad for diabetes, smoking may also play a causative factor in developing diabetes. The new information includes a meta-analysis of 24 prospective cohort studies, looking at over 3.9 million subjects who initially had no diabetes diagnosis. It was discovered that active smokers have a 30%-40% higher risk of developing type 2 diabetes as compared to non-smokers.

Some of the studies compared never smokers to former smokers, light smokers (0-15 cigarettes/day or 0-19 cigarettes/day depending on the study), and heavy smokers (>15 cigarettes/day or >19 cigarettes/day depending on the study). As compared to never smokers, the relative risk of developing diabetes was 1.14 for former smokers, 1.25 for light smokers, and 1.54 for heavy smokers. All risks were found to be statistically significant.

Other studies looked at how many years it would take for a patient’s diabetes risk to decrease to that of a non-smoker after quitting. One large-scale study reported a patient’s risk to fall to that of a non-smoker after 12 years, where another study reported that the risk would fall to normal after 5 years for women and after 10 years for men. This is important to note, since many diabetics worry about the risks of moderate weight gain after quitting smoking. These data seem to show that a moderate short-term weight gain after quitting would be worth it in order to gain the later health benefits of quitting.

The report also tries to identify the potential mechanisms in which smoking puts people at risk for diabetes development. Some of the reasons may include promotion of central obesity, the higher cortisol concentrations in smokers, as well as the inflammatory markers and oxidative stress caused by smoking. Nicotine may also attach to nicotinic receptors on pancreatic cells and reduce insulin secretion directly.

• Current smokers are at a 30%-40% higher risk of developing diabetes as compared to non-smokers.
• Compared to never smokers, former smokers have a relative risk for type 2 diabetes of 1.14, light smokers have a relative risk of 1.25, and heavy smokers have a relative risk of 1.54.
• A smoker’s risk of developing diabetes may fall to that of a non-smoker in 5-12 years after quitting.

The Surgeon General’s 50^th Anniversary report on smoking, Jan. 2014