Smoking significantly increases risk across all type 2 diabetes subtypes.
Smoking has long been linked to serious health problems, but new research shows that the risks extend deeper than many realize. A large study carried out in Sweden, Norway, and Finland found that smoking increases the chances of developing every known form of type 2 diabetes, not just the condition in general. This discovery was presented at the European Association for the Study of Diabetes meeting in Vienna and adds another layer to the already strong evidence connecting tobacco use with chronic disease.
Type 2 diabetes is not a single condition but has been grouped into four subtypes that differ in how they develop and how severe they become. These include severe insulin-resistant diabetes, severe insulin-deficient diabetes, mild obesity-related diabetes, and mild age-related diabetes. Each of these categories has different patterns, but smoking appears to raise the risk across the board. The findings show that people who have ever smoked, whether in the past or currently, were more likely to develop all four subtypes than those who never smoked.
The strongest link was seen in severe insulin-resistant diabetes, the subtype where the body cannot respond properly to insulin. Smokers were more than twice as likely to develop this form compared to non-smokers. In fact, more than a third of these cases could be traced back to smoking. The other subtypes were also affected, though to a lesser degree, with smokers facing about a 20 to 30 percent higher risk depending on the group.
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The study went further by looking at heavy smokers, defined as those with at least 15 years of smoking at a pack a day or the equivalent. Their odds were even worse. Heavy smokers were more than two times as likely to develop severe insulin-resistant diabetes, and their risk for the other subtypes rose by around half. This shows a clear dose-response relationship: the more someone smokes, the greater the danger.
Interestingly, the research also examined how smokeless tobacco, particularly snus, which is widely used in Scandinavia was linked to the disease. Among men in Sweden, high use of snus was linked with increased risk of both severe insulin-deficient and severe insulin-resistant diabetes, suggesting that nicotine and other compounds in tobacco may play a direct role in damaging the body’s ability to regulate blood sugar.
Another important aspect of the research was how genetics influenced the picture. People with a genetic predisposition to type 2 diabetes, poor insulin secretion, or insulin resistance were especially vulnerable if they smoked. Heavy smokers with these genetic risks had more than three times the likelihood of developing severe insulin-resistant diabetes compared to those without the combined factors. This shows how lifestyle and genetics can interact in ways that multiply the harm.
What stands out from this work is the consistency of the results. No matter the subtype, smoking raised the risk. The most pronounced effect was seen in the group where insulin resistance drives the disease, pointing to smoking as a factor that worsens the body’s ability to use insulin effectively. That connection aligns with other studies that show smoking can damage blood vessels, increase inflammation, and impair metabolism, all of which play into the development of diabetes.
The fact that smoking and diabetes are linked carry strong public health implications. Diabetes is already one of the most widespread chronic illnesses worldwide, placing heavy strain on both individuals and healthcare systems. If smoking not only raises the risk of the disease in general but also fuels its most severe forms, then tobacco prevention and cessation programs take on even greater importance. The study suggests that quitting smoking could prevent a large number of future diabetes cases, particularly those in the more harmful categories.
The researchers also show how genetic testing might help identify people who are at especially high risk. Those individuals could benefit from targeted support to stop smoking before lasting damage is done. While lifestyle changes such as diet and exercise remain central to diabetes prevention, this study shows that tobacco use is a powerful factor that cannot be ignored.
The message is clear: smoking does not only harm the lungs or the heart, it reaches into the body’s metabolic systems and fuels one of the most common and costly diseases of modern life. By continuing to smoke, people increase their odds of facing not just one, but all forms of type 2 diabetes, and the risk climbs higher with heavier use. For those already carrying a genetic burden, the danger is multiplied. The research underscores the importance of stepping away from tobacco as a critical part of protecting long-term health.
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Smoking raises the risk of all subtypes of type 2 diabetes
Smoking increases the risk of type 2 diabetes, regardless of its characteristics