Go through these in order and stop at the first one that applies. If you are reading this for someone else, answer for them.
Call emergency services for vomiting, stomach pain, deep or rapid breathing, severe drowsiness, confusion, a seizure, or loss of consciousness.
These symptoms can occur with dangerously abnormal blood glucose or another serious problem.
Seek same-day medical advice if increased hunger occurs with marked thirst, frequent urination, and unplanned weight loss.
This is especially important for a child or teenager, during pregnancy, or if you already have diabetes.
Get urgent help if symptoms do not improve or you cannot safely eat or drink.
Book a routine appointment if increased appetite lasts for several weeks, has no clear explanation, or is causing unwanted weight change.
Arrange an earlier review if it comes with persistent tiredness, tremor, heat intolerance, a fast heartbeat, or changes in bowel habits.
The article also says
Sudden hunger with shaking, sweating, dizziness, or confusion may be low blood glucose.
If you have diabetes, follow your personal low-glucose plan and recheck as instructed.
Every sign above is quoted from the sofidex article on Increased appetite. If you are not sure, err upward — it is always reasonable to be checked.