Smoking is the single most preventable cause of death in the world. For people with diabetes, it is even more dangerous — it dramatically amplifies every cardiovascular, renal, and neuropathic complication that diabetes already causes. If you smoke and have diabetes, quitting is the single most impactful health decision you can make.
How Smoking Worsens Diabetes
The interaction between smoking and diabetes is profoundly harmful. Nicotine and other tobacco chemicals worsen insulin resistance, making blood sugar harder to control. Smoking causes endothelial dysfunction — damage to the inner lining of blood vessels — which accelerates atherosclerosis. It raises LDL cholesterol and triglycerides while lowering protective HDL cholesterol. It promotes inflammation and oxidative stress, both of which are already elevated in diabetes.
The result is a multiplicative — not merely additive — increase in cardiovascular risk. A person with diabetes who smokes has 3–4 times the cardiovascular risk of a non-smoking person with diabetes.
What Happens When You Quit
- 20 minutes: Heart rate and blood pressure drop
- 12 hours: Carbon monoxide levels in blood normalise
- 2–12 weeks: Circulation improves; insulin sensitivity begins to improve
- 1 year: Risk of coronary heart disease halved compared to a smoker
- 5 years: Stroke risk reduced to that of a non-smoker
- 10 years: Lung cancer risk halved; risk of other cancers decreases
Effective Quitting Methods
| Method | Success Rate at 12 months | Notes |
|---|---|---|
| Varenicline (Champix) | ~25–30% | Most effective pharmacotherapy; prescription required |
| NRT + Behavioural Support | ~20–25% | Patches, gum, lozenges; available OTC |
| Bupropion | ~15–20% | Antidepressant with smoking cessation effect |
| Willpower alone | ~3–5% | Least effective; combine with support for best results |
If you have diabetes and you smoke, quitting is the single most powerful action you can take to protect your health. The combination of smoking and diabetes creates a cardiovascular risk that is far greater than the sum of its parts. Use evidence-based methods — varenicline or NRT combined with behavioural support — and ask your GP or diabetes team for help. You do not have to do this alone.

