Smoking doesn’t just harm your lungs and heart—it also increases your risk of developing type 2 diabetes. Like sleep, it is an independent risk factor, meaning it raises diabetes risk regardless of other diet and lifestyle choices, even if they’re otherwise positive.

Smoking and diabetes

Smoking affects the body’s metabolism in multiple ways. It increases insulin resistance and causes inflammation and disruptions in fat metabolism (dyslipidaemia). These processes push blood glucose levels higher and make diabetes more likely to develop. Recent research suggests that smoking-related changes in blood fats and inflammatory markers may explain up to 40% of this increased diabetes risk.

Large studies show that people who smoke have about a 30–50% higher risk of developing type 2 diabetes compared to those who have never smoked, and the risk rises with the number of cigarettes smoked. The risk gradually drops after quitting, showing that it’s never too late to benefit from stopping.

Emerging risk: Vaping

New research points to potential metabolic risks linked to vaping (e-cigarette use). Although evidence is still developing, several international studies have found that people who vape currently have higher odds of prediabetes—even if they’ve never smoked traditional cigarettes. Vaping has been associated with higher insulin resistance in some groups, particularly those who also smoke. Large population studies from Korea found that both smokers and vapers had a higher risk of diabetes, with dual users (those who smoke and vape) showing the highest risk.

Recap

Both smoking and vaping, especially when used together, are linked with poorer blood glucose control and increased risk of diabetes. Quitting smoking and avoiding all nicotine products remain some of the most powerful steps you can take to protect your metabolic health.

If you need help quitting, your doctor is a great place to start. They can guide you to the best options for your health and lifestyle.

Australian quit services

• Pave app — Quit vaping support
• Quitline — Call 13 QUIT (13 7848)
• 13YARN — Support for Aboriginal and Torres Strait Islander peoples. Call 13 92 76

New Zealand quit services

• Quitline NZ — Call 0800 778 778
• Te Hā Ora — Māori smoking cessation support services
• Healthify — Information on quitting smoking and local services
• Smokefree — Find a stop smoking service