Which of the following is a symptom of both diabetes and chronic infection?

Weight loss is a key symptom that can be seen in both diabetes and chronic infections. In diabetes, particularly in uncontrolled type 1 diabetes or late-stage type 2 diabetes, the body is unable to effectively utilize glucose for energy. As a result, it begins to break down fat and muscle for fuel, leading to significant weight loss. In chronic infections, the body often uses energy reserves to mount an immune response. This increased metabolic demand and loss of appetite, common in chronic illnesses, can also lead to weight loss.

Weight gain is typically associated with type 2 diabetes as insulin resistance can lead to increased fat storage, while increased appetite often occurs alongside hyperglycemia in diabetes but does not correlate with chronic infections. Fatigue, while a symptom of both conditions, is not exclusive or uniquely indicative of them, thus weight loss stands out as a commonality.