New research shows that smoking increases the risk of all types of type 2 diabetes, regardless of the specific form the disease takes.
This discovery was presented at the annual meeting of the European Association for the Study of Diabetes (EASD) in Vienna, Austria.
Type 2 diabetes (T2D) is not the same for everyone. Scientists now believe there are four different subtypes of the disease.
These include SIRD (severe insulin-resistant diabetes), which happens when the body doesn’t respond well to insulin; SIDD (severe insulin-deficient diabetes), which involves low insulin levels; MOD (mild obesity-related diabetes), which usually affects younger people who are overweight; and MARD (mild age-related diabetes), which develops later in life.
Even though the symptoms and complications differ across these subtypes, it has not been clear whether risk factors like smoking affect them differently. A new study from researchers in Sweden, Norway, and Finland helps to answer that question.
Using health data from nearly 7,000 people in Norway and Sweden, researchers looked at how smoking and other tobacco use related to the risk of getting each type of T2D. The study included 3,325 people with diabetes and 3,897 without.
The results showed that people who had ever smoked—either currently or in the past—were more likely to develop all four subtypes of T2D than people who had never smoked. The strongest link was with the SIRD subtype. Smokers were more than twice as likely to develop this severe, insulin-resistant form of the disease.
In fact, smoking was estimated to be responsible for more than one-third of all SIRD cases. For the other subtypes, the percentage of cases linked to smoking was less than 15%.
People who smoked heavily (the equivalent of 20 cigarettes a day for 15 years) had even higher risks. Heavy smokers were 2.35 times more likely to develop SIRD than non-smokers, and they also had higher chances of developing the other three subtypes.
The researchers also studied the effects of snus, a type of smokeless tobacco that is common in Scandinavia. In Swedish men, heavy snus use was linked to a higher risk of the more serious forms of diabetes (SIDD and SIRD).
Additionally, the study explored whether people with a genetic risk for diabetes were more vulnerable to smoking. The findings showed that those with both genetic risk and heavy smoking habits were especially likely to develop the SIRD subtype.
For instance, people who had both high genetic risk for low insulin secretion and who smoked heavily were more than three times as likely to develop SIRD.
The study confirms that smoking is harmful no matter which type of type 2 diabetes a person may develop. But it also highlights that those with insulin resistance may be particularly at risk.
Lead researcher Emmy Keysendal said that these findings underline the need for smoking cessation programs, especially for people with a genetic tendency toward diabetes. Knowing one’s genetic risk may help guide more effective prevention strategies in the future.
This new research makes it even clearer: quitting smoking is not only good for your lungs, it’s crucial for protecting your long-term metabolic health.
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