A person with diabetes lacks which hormone?

The correct choice is insulin because this hormone is crucial for regulating blood sugar levels in the body. In individuals with diabetes, particularly type 1 diabetes, the body either does not produce enough insulin or does not produce it at all, leading to elevated blood sugar levels. In type 2 diabetes, the body may not use insulin effectively, which also results in high blood sugar. Insulin is responsible for allowing glucose to enter cells, where it is used for energy. Thus, a lack of this hormone directly contributes to the complications associated with diabetes, such as hyperglycemia and long-term health issues affecting various organs.

Other hormones mentioned, such as cortisol, adrenaline, and estrogen, play important roles in different physiological processes but are not directly related to the primary issue of blood sugar management as insulin is. Cortisol is involved in the body’s stress response, adrenaline helps in the fight-or-flight response, and estrogen regulates various functions in the reproductive system. However, none of these hormones are responsible for the inability to regulate blood glucose levels that is characteristic of diabetes.