What happens when you don’t eat enough and your carbohydrate stores run out!  Typically due to illness, especially with vomiting.

But  can be endocrine cause eg hypopituitarism, adrenal insufficiency. Growth hormone deficiency associated with recurrent hypoglycaemia even before growth failure apparent, associated with sudden death.

If you have excluded glycogen storage disorders (big liver, high lactate), glycogen synthase deficiency (normal liver, high lactate) and organic acidurias (acidosis, encephalopathy, usually high ammonia too), can be idiopathic (usually SGA at birth, thin, presents under 4yr, resolves by 7yr).

If ketones low and fatty acids high, then suggests fatty acid oxidation disorder (but usually just means hypoglycaemia was treated before sample was collected).

Regular meals + night time complex carbo snack, optimize nutrition, carbs if unwell eg Maxijul + Electrolade else Ribena/apple juice.