Past studies show that there are a number of lifestyle factors that may contribute to the development of type 2 diabetes, such as smoking.
There are different subtypes of type 2 diabetes, which can be related to age, insulin resistance, and obesity.
A new study reconfirms smoking as a major risk factor for type 2 diabetes, and says this risk occurs across all four subtypes of the condition.
It also finds that smoke-free tobacco products, such as e-cigarettes and nicotine pouches, can also heighten diabetes risk.
Researchers estimate that about 11% of the world’s population lives with diabetes, with 90% having type 2 diabetes.
Past studies show that there are a number of lifestyle and environmental factors that may contribute to the development of type 2 diabetes, including eating ultra-processed foods, living a sedentary lifestyle, obesity, not getting enough sleep, excessive drinking of alcohol, and smoking.
Now, a new study presented at the annual meeting of the European Association for the Study of Diabetes (EASD) reconfirms smoking as a major risk factor for type 2 diabetes, and says this risk occurs across all four subtypes of the disease.
The findings are yet to be published in a peer-reviewed journal.
For this study, researchers analyzed medical data from more than 3,300 people with type 2 diabetes and almost 3,900 controls, who had been participants in a previous diabetes study in Norway and a case-control study in Sweden.
Study participants were divided into four different type 2 diabetes subtypes:
Mild age-related diabetes (MARD)
Mild obesity-related diabetes (MOD)
Severe insulin-deficient diabetes (SIDD)
Severe insulin-resistant diabetes (SIRD)
Scientists also looked at the smoking status of participants, such as current, past, or nonsmoker.
“We wanted to find out if smoking plays the same role in all subtypes, or if some groups are more vulnerable than others,” Emmy Keysendal, a PhD student at the Institute of Environmental Medicine, Karolinska Institutet, Sweden, and the first author of this study, told Medical News Today.
“This is important because the different subtypes may have distinct underlying disease mechanisms, and learning how smoking is linked to subtypes that differ in characteristics can help us understand the biology of diabetes. It may also help in developing more tailored prevention strategies.”
At the study’s conclusion, researchers found that any participant of any subtype who smoked — either currently or in the past — were at a higher risk of developing type 2 diabetes than those who had never smoked.
When examining the results by subtype, scientists discovered that previous and current smokers doubled their risk of developing SIRD. Ever-smokers also increased their risk for SIDD by 20%, MARD by 27%, and MOD by 29%.
“This finding shows that smoking raises the risk of all forms of type 2 diabetes, and avoiding smoking is likely beneficial for all in prevention,” Keysendal said. “The particularly strong link we saw with SIRD suggests that smoking significantly harms the body’s ability to respond to insulin, since insulin resistance is the defining feature of this subtype.”
And when looking at heavy smokers — those smoking about 20 cigarettes a day for 15 years — their type 2 diabetes risk increased even further. This participant population had a 2.35 greater chance of developing SIRD, 45% higher risk for MARD, 52% for SIDD, and 57% for MOD.
Additionally, researchers examined how the use of smokeless tobacco products — mainly an oral tobacco product called snus — might impact type 2 diabetes risk.
Keysendal and her team found that study participants using smokeless tobacco products had a 19% higher chance of developing SIDD and 13% for SIRD.
“The link between snus and diabetes risk has been studied less than smoking,” Keysendal explained. “Unlike cigarettes, snus is not burned and generally contains fewer harmful substances, but both products deliver nicotine (and equal amounts of nicotine).”
What about vapes and nicotine pouches?
“Our findings suggest that, like smoking, snus raises the risk of type 2 diabetes, which points to nicotine as a possible driver, particularly through its effects on insulin resistance. This is an important finding considering the rise in the use of products like e-cigarettes and nicotine pouches that are marketed as tobacco-free and potentially less harmful, yet contain high doses of nicotine.”
— Emmy Keysendal, first author
“We still know very little about how risk factors differ between the subtypes of type 2 diabetes and how they interact with genetic risk,” she continued. “In our future research, we will continue to investigate how modifiable risk factors combine with genetics in shaping the different forms of diabetes, as this knowledge could help improve prevention.”
MNT spoke with David Cutler, MD, a board certified family medicine physician at Providence Saint John’s Health Center in Santa Monica, CA, who commented that his first reaction to any study like this is to wonder whether this is simply an association or a cause-and-effect relationship.
“Because where there are many uncontrolled variables and people are doing other behaviors besides smoking, you don’t know if diet or exercise level or weight control might also be having an impact on these people, especially where something like smoking may also impact those behaviors,” Cutler explained.
Cutler said that the potential impact of smoking in particular is important for researchers to continue to study because there’s a myth out there that, because smoking may help control a person’s appetite and weight, it may also reduce their risk of diabetes.
“That’s clearly not true,” he continued. “But many people believe it to be true, and I think this particular study helps destroy that myth.”
“Next steps for this research, I think looking at non-smoking causes that increase the risk of type 2 diabetes, which we already know about, things like people’s weight and their diet, their activity levels, and there are certainly genetic factors, to look into those things to recognize people who are at high risk and to make them more aware of the need to change known behaviors like diet and exercise, which can impact their chance of developing and worsening their diabetes,” Cutler added.