NANP Board Practice Exam 2025 - Free NANP Board Practice Questions and Study Guide

Glucagon is primarily responsible for increasing blood glucose levels. It is a hormone produced by the alpha cells of the pancreas and plays a crucial role in glucose homeostasis. When blood glucose levels drop, glucagon is released into the bloodstream and stimulates the liver to convert stored glycogen into glucose, a process known as glycogenolysis. Additionally, glucagon promotes gluconeogenesis, the production of glucose from non-carbohydrate sources, further increasing blood sugar levels.

In contrast, insulin is the hormone that lowers blood glucose levels by facilitating the uptake of glucose into cells for energy use or storage as glycogen in the liver and muscles. Melatonin primarily regulates sleep-wake cycles and does not have a direct role in glucose metabolism. Thyroxine, a hormone produced by the thyroid gland, influences metabolism but is not the primary hormone for adjusting blood glucose levels. Thus, glucagon's direct involvement in raising blood glucose makes it the correct answer to the question.