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People who smoke have a 30% to 40% likelihood of developing type 2 diabetes compared to non-smokers, with the amount of smoking increasing the risk. Additionally, for people already living with diabetes, smoking can increase the risk of developing complications.

How smoking can lead to type 2 diabetes

Numerous studies have explored the link between smoking and glucose control. One such study, the European Investigation into Cancer (EPIC-Norfolk) study, a comprehensive cross-sectional study of men and women, found that cigarette smoking raised HbA1c levels. Both male and female smokers experienced similar increases in HbA1c, with levels rising by 0.12% for every 20 pack-years of smoking, regardless of gender.

Because nicotine, a key component of cigarettes, impedes the body’s insulin response, cells then become resistant to insulin. This, in turn, increases glucose levels, eventually contributing to the development of type 2 diabetes. Additionally, chemicals in cigarettes can damage cells and cause inflammation, impairing insulin response. Research suggests that smoking is associated with a higher risk of central obesity, another risk factor for type 2 diabetes, even in people who are not overweight.

The benefits of quitting

Quitting smoking offers numerous health benefits, and the body begins to heal as soon as you stop. Within 20 minutes, heart rate and blood pressure drop, reducing the strain on the cardiovascular system. After 12 hours, levels of carbon monoxide in the blood, a toxic gas found in cigarette smoke, return to normal. Circulation and lung function improve within two weeks to three months, making physical activity more accessible. A year after quitting, any risk of heart disease halves compared to people who continue to smoke. Furthermore, insulin resistance is reduced, making it easier to manage glucose levels. People with diabetes may need to monitor these more frequently after quitting, as levels may initially fluctuate before stabilising.

Health professionals are key to educating people with type 2 diabetes on the harmful effects of tobacco use, as well as the benefits of quitting tobacco. And policymakers should implement effective tobacco control measures to protect populations, particularly the most vulnerable, against exposure to tobacco smoke,`` Rebekka Aarsand, No Tobacco Unit, Department of Health Promotion, WHO.

The impact of smoking on diabetes-related complications

Smoking increases the risk of developing complications associated with diabetes.

  • Cardiovascular disease (CVD), the number one diabetes-related complication, is closely linked to smoking. The combination of diabetes and smoking increases the risk of early-onset microvascular complications and worsens existing complications.
  • Smoking plays a detrimental role in the onset and progression of diabetic nephropathy, a complication that can lead to kidney failure.
  • Smoking contributes to nerve damage, known as diabetic neuropathy. This impairs blood circulation and nerve function in the feet, increasing the risk of foot ulcers, infections and lower limb amputations.
  • Smoking can damage blood vessels in the retina, potentially leading to diabetic retinopathy and vision loss.
  • The harmful effects of smoking extend to oral health, as it hinders the body’s healing ability and increases the risk of oral complications and infections.
Second-hand smoke and type 2 diabetes

Not only does smoking directly impact the smoker, but exposure to second-hand smoke (SHS) also poses risks, including an increased likelihood of developing type 2 diabetes. A series of studies revealed that non-smokers exposed to SHS showed a 22% increased prevalence of type 2 diabetes compared with those who reported no exposure. Second-hand smoke contains over 7,000 chemical components, many of which are harmful. Exposure to SHS has also been shown to increase the risk of developing complications associated with type 2 diabetes.

Smokeless tobacco, new and emerging nicotine and tobacco products

Smokeless tobacco, like chewing and snuff, is linked to a higher risk of developing type 2 diabetes due to nicotine addiction. Meanwhile, new nicotine and tobacco products, such as e-cigarettes and heated tobacco products (HTPs), have shown indications of increasing the risk of diabetes and its complications. However, further investigation is needed as to their link to increased glucose intolerance and the risk of developing type 2 diabetes.

Strategies to stop

Quitting smoking can be challenging. Nicotine replacement products, such as gum, patches, and lozenges, can significantly increase the chances of quitting tobacco. However, it is essential to consult with a healthcare professional, especially for people with diabetes, as nicotine replacement products can raise glucose levels. Support from friends, family, and healthcare providers is crucial during this period. Additionally, resources such as free apps and accessing free coaching through helplines can provide valuable assistance.

The importance of population-level interventions

Addressing the link between smoking and type 2 diabetes requires comprehensive population-level interventions. The World Health Organization (WHO) offers tools for implementing the WHO Framework Convention on Tobacco Control, which includes measures to reduce the demand for tobacco. Collaboration among healthcare professionals and integrating evidence-based strategies for behaviour change in diabetes management can further support people in quitting smoking. Moreover, advocating to ensure better policies and programmes to reduce and prevent tobacco use will protect all individuals from the risk of developing type 2 diabetes and diabetes-related complications.

Learn more about the health impact of tobacco as well as population-level and health systems intervention. The WHO tobacco knowledge summary, jointly developed by IDF, WHO and the University of Newcastle, outlines the connection between tobacco use and diabetes. It also describes the effectiveness of interventions to reduce tobacco use and tobacco-related complications.

Download the summary here.


Justine Evans is Content Editor at the International Diabetes Federation

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