Smoking May Raise Diabetes Risk by 36%

Almost 20% of Americans use tobacco products, which is one of the leading causes of preventable disease and death in the U.S. We know smoking increases the risk of cancer and lung and heart diseases; smokeless tobacco increases the risk of cancers of the mouth, esophagus and pancreas. 

There is also evidence from previous studies that smoking increases the risk of type 2 diabetes. But what if someone both smokes and drinks alcohol regularly? Does that increase the risk even more? After all, excessive alcohol intake has also been implicated in increasing the risk of chronic disease and illness, though its connection to diabetes remains unknown.

Scientists from Spain and France wanted to explore whether smoking and alcohol, together and separately, increased the risk for type 2 diabetes. They published their findings in the American Journal of Preventive Medicine. Let’s break down what they found. 

How Was This Study Conducted?

Researchers drew data from a cohort in a long-running, ongoing French study called the NutriNet-Santé study. This study began in 2009 and is continuously recruiting new participants to this day. For this current study, researchers used data from over 110,000 participants, 79% of them women, with an average age of 43. Each participant was followed for an average of 7.5 years. 

Participants filled out several online questionnaires, including ones for diet, physical activity, demographics and lifestyle, which included smoking status and alcohol intake. Responses for alcohol intake were <2 or ≥2 portions/day, and <10 or ≥10 portions/week; researchers then transposed these responses into grams of ethanol per day. 

Options for smoking included whether the participant had ever smoked, if they smoked currently or if they were a former smoker. If the participant was a former or current smoker, a questionnaire assessed how many cigarettes per day they smoked. Based on their responses, researchers grouped participants according to smoking status alone and alcohol intake alone. Researchers also looked at the combined effects of heavy smoking (≥20 cigarettes/day) and heavy drinking (>8 and >15 portions/week for women and men, respectively).

For type 2 diabetes diagnoses, researchers instructed participants to report any health events, medical treatments or hospitalizations via the annual health status questionnaire. They could also provide health-related information at any time via the online health status interface. In addition, researchers collected information from the national health insurance system database.

What Did This Study Find?

After running statistical analyses, researchers found no significant connection between alcohol intake and diabetes. Nor was there a higher risk between the combined smoking and drinking groups and diabetes.

They did, however, find that people who formerly or currently smoke had a 36% higher risk of developing type 2 diabetes compared to those who never smoked. And those who smoked heavily had over twice the risk of those who smoked lightly or moderately. 

There are several limitations to this study. First, the study consisted mostly of women, only 6% of whom exceeded the recommended upper limit for alcohol intake. This means that there might not have been a large enough mixed sample size to get accurate results regarding alcohol intake and diabetes. Also, self-reported alcohol intake is often underreported. Scientists also note that type 2 diabetes incidence may be under-represented in the NutriNet-Santé cohort compared to the general French population. 

How Does This Apply to Real Life?

While this study didn’t find a strong connection between alcohol intake and diabetes, we know alcohol comes with other risks. For example, alcohol has been linked to cancer and brain damage. It can also contribute to chronic inflammation, which in turn increases chronic disease risk. 

Study authors also note that Mediterranean countries, like the ones included in this study, tend to drink alcohol with meals. They point out previous studies that showed a reduced risk of diabetes when alcohol, especially wine, was consumed in moderate amounts with meals, and feel that this may be one of the reasons no connection was found in this study. Still, the downsides outweigh any possible health benefits when it comes to drinking alcohol.

Regarding smoking, the results of this study are also in line with previous research. Study authors believe smoking may increase diabetes risk due to the effects nicotine has on the lining of blood vessels and sympathetic nervous system stimulation. Sympathetic nervous system stimulation leads to increases in cortisol (the stress hormone) and growth hormone secretion, resulting in insulin resistance, higher triglycerides and lower HDL cholesterol (the helpful kind of cholesterol). These are all known risk factors for type 2 diabetes. 

If you use tobacco products and have a desire to quit, there are lots of resources available to help you, including those from the American Lung Association. When changing any habit, it can be helpful to seek outside support and even see a healthcare provider who can offer help and advice.

It also helps to have a strong “why” regarding why you want to quit smoking (or change any habit). Ask yourself why you want to quit, then ask why that answer is important to you. Continue asking until you get to your deeper why—your best motivation to stop smoking. That reasoning can be an anchor on days when you’re tempted to smoke. 

Besides smoking, we know other lifestyle behaviors may also increase your risk of diabetes, including a diet high in added sugar and saturated fat, a lack of physical activity and too little quality sleep. The antidote to these habits is to eat a nutrient-dense diet, move your body more often (including strength training) and get plenty of quality sleep by improving your sleep habits. It’s also important to stay well-hydrated, as dehydration can increase blood sugar levels.

Our Expert Take

This study suggests that smoking significantly increases your risk of diabetes. Current heavy smokers had the highest risk, but even former smokers showed an increased risk. If you’re a current smoker and desire to quit, get help doing so if you find it too difficult to do on your own. And whether you smoke, used to smoke, or have never smoked, engaging in healthy habits like regular physical activity, getting plenty of quality sleep and eating a variety of whole, nutritious foods will go a long way toward reducing your risk of diabetes.