Diabetes, smoking, and vaping

By Credentialled Diabetes Educator & Registered Nurse, Carolien Koreneff

Smoking affects everyone but for people living with diabetes, the impact can be even stronger. Smoking, vaping, and even cigars, can all influence glucose levels, insulin sensitivity, and diabetes complications. The good news? Understanding how these habits affect the body can help make choices that support good health and confidence.

Let’s break down what the research says, in simple, practical terms.

How smoking affects glucose levels

Every time we breathe in cigarette smoke, our body is exposed to chemicals that make it harder for insulin to work. When insulin can’t do its job, glucose stays in the bloodstream instead of moving into the cells for energy. That is called insulin resistance, and it makes diabetes much harder to manage.

Research shows that some of the chemicals in cigarette smoke, especially a group called polycyclic aromatic hydrocarbons (PAHs), can change how the liver processes certain diabetes medicines. That means medications may act differently in the body of a person who smokes.

What are Polycyclic aromatic hydrocarbons? PAHs are chemicals created when things burn — like tobacco, wood, petrol, and even charred foods. They can interfere with insulin and may affect how diabetes medicines work. They’re also linked with inflammation and long‑term health problems. In short: they are dangerous for our bodies, and smoking is a major source of PAH exposure.

Another study found that smoking doesn’t just interfere with insulin — it may also damage the beta cells (the cells responsible for making insulin) in the pancreas. That damage can increase the risk of developing type 2 diabetes and make managing diabetes more complicated.

Day‑to‑day glucose swings: why smoking makes glucose levels more unpredictable

If you live with diabetes, you probably know the feeling of glucose levels going up and down unpredictably. Smoking can make these swings more frequent.

A 2024 study found that people with type 1 diabetes who smoke spend less time in their target glucose range and have higher HbA1c levels compared with non‑smokers.

Vaping isn’t a free pass either. Recent research from the United States shows that vaping increases the risk of pre-diabetes — an early warning sign that glucose levels are creeping too high. While vaping alone wasn’t clearly linked with higher diabetes rates, people who both vape and smoke cigarettes had the highest odds of developing diabetes.

Smoking also ramps up inflammation in the body, which can push glucose levels higher and increase the risk of complications. And interestingly, studies show that smoking helps explain why people with lower incomes may have worse glucose outcomes; highlighting how stress, access to care, and environment all play a role.

As one researcher put it: “This is not just about the lungs anymore — it’s about the entire body and metabolic health.”

Does smoking increase the risk of type 2 diabetes?

Yes. For people with pre‑diabetes or risk factors for diabetes, smoking adds extra pressure to their system. Studies clearly show that smoking increases the risk of developing type 2 diabetes — and that risk is even higher when smoking is combined with alcohol use.

Smoking and diabetes complications

Smoking affects blood flow throughout the body, narrowing vessels and making it harder for oxygen and nutrients to reach important organs. For people with diabetes, this can speed up complications such as:

• heart disease
• kidney damage
• nerve damage
• foot ulcers
• vision loss

Smoking and high glucose together create the “perfect storm” for complications to develop sooner and progress faster.

Vaping, cigars, cigarettes: are some safer than others?

Short answer: No. All forms of smoking affect glucose levels and health in general.

But they do so in slightly different ways.

Vaping (E‑cigarettes)

Many people choose vaping because they believe it’s safer. But research shows:

• Vaping alone increases the risk of pre-diabetes by about 7%.
• It is linked with short‑term insulin resistance and weight gain.
• Dual use (vaping and smoking) increases risk the most — about 28% higher for prediabetes, and a higher likelihood of a diabetes diagnosis.

Vaping doesn’t just affect the lungs — it influences whole‑body metabolism.

Cigarettes

Cigarette smoking is linked with a 15% higher risk of pre-diabetes.

Cigarette smoke:

• increases inflammation
• reduces insulin sensitivity
• damages blood vessels
• worsens glucose levels in both type 1 and type 2 diabetes

Cigars

Even if the person does not inhale deeply, cigars are not harmless either! Cigar smoke contains the same harmful chemicals and nicotine as cigarettes. The risk of developing prediabetes is also around 15%.

Quick comparison

Product type	Increase in pre-diabetes risk	What it means
Vaping only	~7%	Can affect insulin response and weight
Cigarettes	~15%	Strong evidence of insulin resistance and complications
Cigars	~15%	Same harmful chemicals as cigarettes
Vaping + Smoking	~28%	Highest risk; combined metabolic stress

What this means for your clients

All smoking products, including vapes, can:

• raise glucose levels
• reduce insulin sensitivity
• make diabetes harder to manage
• increase the risk of long‑term complications

The encouraging news? Quitting helps. Even small changes can reduce risks and improve day‑to‑day glucose stability.

Regular physical activity can also reduce the risk of pre‑diabetes in smokers by around 8% — proof that healthy habits can offset some of the damage.

The benefits of quitting

Quitting smoking is one of the most powerful gifts a smoker can give their body — and the benefits often start within weeks.

After quitting:

• insulin sensitivity improves
• diabetes medicines work more effectively
• glucose patterns stabilise
• the risk of heart, kidney, and nerve complications drops

Because of metabolism changes after quitting, it is a good idea to for people with diabetes who quit smoking to check their glucose more often, and talk to a diabetes educator or doctor if glucose levels shift.

Clients don’t have to quit alone

Quitting isn’t easy — especially if stress or glucose swings are already part of life. But support makes a huge difference.

Helpful options include:

• nicotine replacement therapy
• stop‑smoking medications
• group or behavioural support
• stress‑management tools
• personalised advice from your diabetes care team

A diabetes educator can help your clients create a plan that fits their lifestyle, goals, and health needs.

Final thoughts

Smoking adds strain to the body and makes diabetes harder to manage — and neither vaping nor cigars are safer alternatives. But every step toward cutting back or quitting puts your client back in control.

If your client is thinking about quitting, get them to reach out to their diabetes care team. Everyone deserves support, compassion, and a plan that helps them live well with diabetes — on their own terms.