| Insulin resistance & glucose control | Strongly increases insulin resistance; worsens HbA1c and glycaemic variability. | Nicotine may cause mild insulin resistance, but less than smoking. Evidence mixed and less studied. |
| Risk of developing type 2 diabetes | Increases risk by ~30–40%. | No clear evidence yet, but nicotine exposure may contribute modestly. Risk is likely lower than smoking. |
| Cardiovascular risk (heart attack, stroke, peripheral artery disease) | Very high – smoking is a major independent risk factor. | Lower than smoking, but nicotine still raises BP and HR. Long-term vascular impact not fully known. |
| Microvascular complications (eyes, kidneys, nerves) | Strong evidence for faster progression and higher complication rates. | Limited evidence. Likely lower risk than smoking, but potential effects from nicotine/oxidative stress not excluded. |
| Cancer risk | High: lung, bladder, pancreas, kidney, others. | Much lower: far fewer carcinogens than smoke. Long-term risk still under study. |
| Lung health | Causes COPD, emphysema, chronic bronchitis. | No tar/CO, but risk of lung irritation, asthma exacerbation, and rare vaping-related lung injury (EVALI). |
| Addiction & dependence | Highly addictive (nicotine + smoke additives). | Nicotine addictive. Dependence possible, sometimes harder to taper due to frequent dosing patterns. |
| Overall harm (in diabetes context) | Major negative effect on outcomes. Strongly advised to quit. | Safer than smoking, but not harmless. Best as a quit tool → aim to stop vaping too. |
