[Smoking and nicotine use, heated tobacco products, psychological and socioeconomic aspects of dependence, alcohol, infections, vaccination and diabetes mellitus (Update 2026)].

Smoking and passive smoking significantly increase both the incidence of diabetes and the risk of late complications. While complete smoking and nicotine cessation may lead to weight gain and an increased risk of diabetes, it nevertheless reduces cardiovascular and all-cause mortality. The basic diagnostic assessment (Fagerström test, exhaled carbon monoxide) is essential for successful smoking cessation. Evidence-based pharmacological options include varenicline, nicotine replacement therapy, bupropion and cytisine; glucagon-like peptide 1 (GLP-1) receptor agonists may be used as adjunctive treatment for weight control following smoking cessation. Neither heated tobacco products, e‑cigarettes nor smokeless nicotine products (nicotine pouches) are harmless alternatives, they are also associated with an increased risk of diabetes, morbidity, and mortality. Socioeconomic and psychological factors play a significant role in addictive behavior, including smoking, nicotine use and alcohol consumption. Moderate alcohol consumption appears to reduce the risk of diabetes and cardiovascular disease but selection bias and underreporting likely overestimate this effect. Dose-dependent risks, particularly through cancer, liver disease and infections predominate. Infections occur more frequently in individuals with diabetes, often with greater severity and atypical presentation. Unexplained hyperglycemia should always prompt consideration of an infection. Vaccinations are of even greater health relevance for patients with diabetes than for those without.