Denise just received the results of a complete physical that found her body is not producing enough insulin. Which of the following endocrine glands is affecting her body's ability to produce insulin?

A) adrenal
B) thymus
C) thyroid
D) pancreas

The pancreas is responsible for producing insulin, so if the body is not producing enough, it is likely a problem with the pancreas. The adrenal gland is responsible for producing hormones like cortisol and adrenaline, the thymus produces hormones involved in immune function, and the thyroid produces hormones involved in metabolism. None of these organs directly produce or regulate insulin.