Diabetes mellitus is an example of a metabolic disease. It is a chronic condition that affects how the body processes glucose (sugar) in the blood. There are two main types of diabetes: type 1, which is an autoimmune condition where the body does not produce insulin, and type 2, which is characterized by insulin resistance and high blood sugar levels. Diabetes can lead to serious complications such as heart disease, kidney failure, and nerve damage if not properly managed.