Dear Madam, Thank you for your query.
I can understand your concern for your dad. by analyzing your dad symptoms, it may be either postprandial hypoglycemia or sleepiness due to obstructive sleep apnea. If your father is obese, second possibility is likely. Anyway if it of recent onset and affecting his lifestyle, it is better to get evaluated by your physician. He may ask you to do self monitoring of glucose to rule out postprandial hypoglycemia or sleep study to rule out sleep apnea if indicated.
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