Final answer:
Caffeine can have a hyperglycemic effect by raising blood glucose levels through the stimulation of glucagon release and interference with the sleep-wake cycle.
Step-by-step explanation:
Some researchers think that caffeine can have a hyperglycemic effect due to its ability to raise blood glucose levels. Caffeine stimulates the release of the hormone glucagon, which raises blood glucose levels by promoting the breakdown of glycogen into glucose. This process is known as glycogenolysis. Additionally, caffeine can interfere with the sleep-wake cycle and cause shakiness, anxiety, and insomnia, which can indirectly affect blood glucose regulation.