Insulin or Oral Hypoglycemic Overdose: This is the most likely diagnosis given the significant drop in blood glucose levels at night, suggesting an excessive effect of glucose-lowering medications. The high daytime blood glucose levels could indicate either inadequate dosing for daytime control or a rebound effect.

Dawn Phenomenon with Overcorrection: The dawn phenomenon is a natural increase in blood glucose during the early morning hours due to the release of certain hormones. If the patient is overcorrecting for this anticipated rise with too much insulin or oral hypoglycemics, it could lead to hypoglycemia later in the night.
Somogyi Effect: This is a rebound hyperglycemia that occurs after an episode of hypoglycemia, often due to excessive insulin administration. It could explain the high daytime blood glucose levels following a nocturnal hypoglycemic episode.
Inadequate Basal Insulin Coverage: If a patient is on insulin therapy, inadequate basal insulin dosing could lead to high daytime glucose levels, while too much short-acting insulin at dinner could cause nocturnal hypoglycemia.

Hypopituitarism or Adrenal Insufficiency: Although rare, these conditions can lead to hypoglycemia due to the lack of counter-regulatory hormones (like cortisol and growth hormone) that normally help increase blood glucose levels during fasting periods.
Insulinoma: A rare tumor of the pancreas that produces excess insulin, leading to episodes of hypoglycemia, which could be more pronounced at night due to fasting.

Glycogen Storage Diseases: Certain types of these diseases can lead to hypoglycemia, particularly during fasting periods, due to the inability to properly break down glycogen to glucose.
Fatty Acid Oxidation Disorders: These are genetic disorders that affect the body's ability to convert fat to energy, potentially leading to hypoglycemia during periods of fasting or when glucose is in low supply.