A condition characterized by a deficiency of insulin in the body is diabetes mellitus. This condition affects how the body uses glucose, leading to elevated blood sugar levels. In type 1 diabetes, the body produces little to no insulin due to autoimmune destruction of the pancreatic cells. Type 2 diabetes, on the other hand, involves insulin resistance, where cells do not respond effectively to this hormone. Managing diabetes is crucial to avoid complications such as neuropathy, nephropathy, and cardiovascular issues.