Psoriasis is a chronic inflammatory skin disease affecting 2-3% of worldwide population. Moderate to severe psoriasis is frequently associated with metabolic disorders including diabetes, obesity, dyslipidaemia, metabolic syndrome and non-alcoholic fatty liver disease. In particular, the prevalence of diabetes in patients with psoriasis ranges from 5 to 54%. Most of the studies found that the prevalence of diabetes is higher in patients with moderate to severe psoriasis compared to mild disease. The association between psoriasis and diabetes could be explained considering several factors including a common genetic background, the high prevalence of metabolic risk factors for diabetes in patients with psoriasis as well as unhealthy life-styles such heavy drinking, over-eating and sedentary, which are common in patients with psoriasis. From a clinical prospective, the understanding of the patients in the context of metabolic comorbidities including diabetes is very important to ensure that treatment is tailored to meet the individual patient needs. Indeed, some pharmacological treatments may negatively affect metabolic comorbidities, and have important interactions with drugs that are commonly used to treat them. Non-pharmacological intervention such as diet and physical exercise could both improve the response to treatments for psoriasis and reduce the risk of diabetes and cardiovascular events.