Medical review by Dr. Mike Natter.
Most of us know that smoking is bad for our health. It is less well-known that smoking is especially dangerous for people with diabetes.
This article will outline why smoking is uniquely risky for people with diabetes, and show why quitting can make such a big difference.
Smoking Is Bad for Everyone
Let’s get this out of the way: smoking is awful for everyone’s health. According to the Centers for Disease Control and Prevention (CDC), tobacco use is the leading cause of preventable death in the United States. The life expectancy of regular smokers is “at least 10 years shorter than for nonsmokers.”
Smoking is the leading cause of lung diseases, including lung cancer, COPD, emphysema, and chronic bronchitis. Smoking also contributes to the growth and development of many other types of cancer, including cancers of the mouth and throat, voice box, esophagus, and stomach, among others. Perhaps most importantly, smoking is also known to significantly contribute to cardiovascular disease, including heart attack and stroke.
We’ve known most of this for generations. And yet, about 31 million Americans still smoke tobacco cigarettes regularly, and smoking rates are much higher in many other countries.
Smoking and Blood Sugar Control
Smoking can have a significant effect on insulin resistance, metabolic health, and blood sugar control.
There is a strong correlation between smoking and type 2 diabetes rates. The FDA reports that “smokers are 30 to 40 percent more likely to develop type 2 diabetes than nonsmokers,” a declaration based on studies like this 2015 meta-analysis of data from millions of patients. Other study has shown that cigarettes have a “dose-respondent” relationship with diabetes risk, which is to say, the more you smoke, the higher the risk.
Scientists are still working to tease out the causal links that explain exactly how smoking increases diabetes risks. The chemicals from cigarette smoke result in inflammation and oxidative stress that may accelerate glucose intolerance and insulin resistance, as well as exacerbate diabetes-related complications. Recent experimentation in rodents has also suggested that nicotine triggers a “diabetes-like” glycemic dysfunction.
Whatever the details, we do know from many studies that smoking “seems to markedly aggravate insulin resistance” in patients with type 2 diabetes and is associated with worse glucose control in patients with type 1 diabetes. Smokers with diabetes, both type 1 and type 2, have higher A1Cs.
These glucose effects are not immediate – a cigarette is not likely to raise your blood sugar – but the evidence is clear: Chronic smoking leads to a significant deterioration of glycemic control.
Smoking and Diabetes Complications
This is where it gets really scary: smoking dramatically accelerates the development of certain diabetes complications.
Smoking and diabetes are both huge risk factors for early death from cardiovascular disease, and when they occur in the same body, the two health disturbances appear to reinforce each other in a synergistic fashion.
A meta-analysis found that people with type 1 or type 2 diabetes that also smoke have a roughly 50% increased risk of early death from a variety of cardiovascular diseases, including heart attack and stroke, as well as chronic conditions like heart disease and heart failure. Remember, that’s on top of the already wildly elevated cardiovascular risks associated with diabetes.
Cardiovascular disease is the leading cause of death for people with diabetes – a risk that is profoundly increased by smoking. This 2017 Finnish study found that smokers with type 2 diabetes were six to seven times as likely to die early of cardiovascular disease than people without either condition.
Smoking also accelerates the progression of kidney dysfunction (nephropathy) in patients with diabetes. Kidney decline is one of the most uncomfortable (and ultimately deadly) complications of diabetes.
A 2019 meta-analysis of 13 studies found that people with type 2 diabetes who smoked were about twice as likely to develop microalbuminuria, an early sign of kidney disease, as compared to those who didn’t. The analysis indicated that smoking was a more significant risk factor than many other health parameters, including glycemic control, age, cholesterol, and weight.
We find similarly enhanced risks in type 1 diabetes. In a study of 943 patients with T1D, current smokers were about four times as likely to develop microalbuminuria. A larger Finnish study found that the effect was somewhat less dramatic, but the risk still nearly doubled. It also determined that the risks increase along with smoking volume.
Smoking may also increase the risks of other complications:
Several studies have identified an association between smoking and diabetic neuropathy. The connection seems stronger in patients with type 1 diabetes.
Smoking also accelerates the development of diabetic retinopathy in type 1 diabetes, but apparently not in type 2.
Cannabis (Marijuana) and Diabetes
How about smoked cannabis (marijuana) and diabetes outcomes? The evidence is less than clear. Here’s a quick review of what researchers believe:
Marijuana smoke does contain carcinogenic compounds, many of which are also found in cigarette smoke. But there is little evidence that marijuana triggers major long-term health problems, including lung cancer, perhaps because cannabis users typically smoke far less per day than cigarette users. Regular marijuana smokers, however, do experience higher rates of bronchitis and lung irritation.
It’s unclear if cannabis products have a negative effect on glycemic control. A 2020 review concluded that cannabis may negatively impact the metabolism, but the evidence was rated as merely “poor to fair” quality. Unlike cigarette smoke, cannabis is not believed to contribute to the development of type 2 diabetes.
It’s also important to note that cannabis is associated with an increased risk of DKA for patients with type 1 diabetes. That is partially due to the known risk of cannabis hyperemesis syndrome (CHS), but potentially also to the effects of intoxication.
We’re not aware of any evidence that cannabis use is associated with long-term microvascular diabetic complications such as retinopathy or kidney disease. That isn’t necessarily an indication that cannabis is wholesome; it may just indicate that the topic hasn’t been studied much. Similarly, there is little or no evidence linking cannabis smoke to an elevated risk of death from cardiovascular disease. Even so, the substance has been linked with multiple adverse cardiac effects. With the legalization of cannabis throughout much of the United States, we can hope that there will be further study to clarify the topic.
In summary, the scientific case against smoked cannabis (marijuana) is not nearly as strong as the case against cigarettes. But even though the evidence is somewhat murky, there’s little doubt that cannabis smoke has multiple harmful effects. Diabetes authorities caution against the use of recreational cannabis, especially when smoked.
We have an entire article on the topic: Marijuana and Diabetes: What You Need to Know.
Vaping and Other Cigarette Alternatives
Cigarettes are not the only way to smoke tobacco. Vaping and hookahs have exploded in popularity in recent years, and some old-school readers might still prefer pipes and cigars.
Johns Hopkins Medicine reports that “vaping is less harmful than smoking, but it’s still not safe.” E-cigarettes and related devices contain many fewer chemicals than cigarettes, but they are still highly associated with lung injuries.
Does vaping cause cardiovascular disease? The evidence is mixed. Some studies have found no relationship, while others the opposite. Researchers agree that more studies are needed to settle the question. Because vaping is comparatively new, we have not yet accumulated enough quality data on long-term health effects. For the same reasons, it is currently unknown if vaping enhances the risks of diabetic complications, but there is some preliminary evidence that vaping increases blood glucose levels.
Public health experts, by the way, are very much split on the use of e-cigarettes to help quit smoking.
Cigars, Pipes, and Hookahs
There is much less evidence about pipe and cigar smoking, but experts surmise that the behavior is at least somewhat more healthy than smoking cigarettes because users rarely inhale their smoke. A British 2003 study found that pipe and cigar smoking was less risky than “light” cigarette smoking (fewer than 20 cigarettes per day), but still significantly more dangerous than not smoking at all.
Hookah smoke, despite its mild water-filtered feel, is not considered any safer than cigarettes.
Reduce Your Risk and Improve Your Health by Quitting Smoking
The best thing to do if you have diabetes and smoke is to quit immediately!
Quitting smoking confers rapid health benefits, especially improvement in cardiovascular risk factors. A 2015 meta-analysis found that while people with diabetes that are currently smoking are about 50% more likely to suffer cardiovascular disease, former smokers cut that risk down to 10-20%, and the risk of stroke disappears entirely. Many other studies have shown similar results, in people both with and without diabetes.
The evidence supporting an improvement in microvascular complications is less comprehensive but still encouraging. Small studies have shown, for example, that smoking cessation can not only protect against kidney disease in type 2 diabetes, it can even ameliorate kidney disease.
One word of warning: quitting smoking does not guarantee an immediate improvement in glycemic control. In fact, some patients only see their blood sugar numbers get worse after quitting. Some of these issues are caused by the weight gain that is so common after smoking cessation, but not all of them. A 2015 study in The Lancet found that successful quitters saw their A1C rise by 0.2 percent within a year, even when adjusted for weight gain. It remained elevated for two additional years.
The truth is, it can take a while for your glucose metabolism to rebound from years of chronic smoking. A 2017 study found that former smokers needed to stick with it for about a decade for glycemic control to return to the level enjoyed by non-smokers. For these reasons, experts suggest that it might be a good idea to embark on a weight loss or maintenance program at the same time that you attempt to quit smoking.
The health benefits of smoking cessation continue to accrue over the years. The American Cancer Society has put together a helpful timeline of the health benefits of quitting, showing that some improvements occur overnight, while others grow for over a decade. After about fifteen years, former smokers have about the same risk of heart disease as never-smokers.
There are many resources available to people who want to quit smoking.
The US government maintains an online hub, Smokefree.gov, where you can find information on nicotine replacement therapy, helplines, apps, texting programs, and support groups. If government info isn’t your style, social media is full of communities dedicated to smoking cessation. There are many books, podcasts, and Youtube videos on the topic.
We also recommend our partner Everyday Health, which maintains a generous library of articles on how to quit smoking.
The American Diabetes Association recommends one of the following approaches:
Go cold turkey. Quitting all at once works for some people.
Taper off. Quit smoking gradually by cutting back over several weeks.
Use a nicotine patch, gum, inhaler or spray. Or ask your doctor for a prescription medicine.
Ask your doctor about counseling, acupuncture or hypnosis.
Whatever it takes, give yourself grace: a study revealed that smokers try to quit an average of 30 times before they succeed. Living with the stress of diabetes can make those attempts even more challenging, but even more worthwhile for you and your health.
Quit smoking not only for yourself but for the health of your family as well. Lean on your loved ones for support, and work with your doctor to find a treatment plan that will work for you, minimize withdrawal symptoms, and make the transition to a smoke-free life easier.
Quitting smoking may be one of the hardest tasks you ever undertake, but the benefits are absolutely clear: a longer, healthier life.