Severijn wrote:About 8.3 % of people in the US have diabetes I or II; I don't know if hypoglycemia is included in that number. About 10 to 15 % of people get depression over their lifetime.
Even if diabetes/hypoglycemia is always and directly the cause of depression, there's still about 2 to 7 % of people that have depression that do not have any kind of problems with their blood sugar. But I doubt that people with hypoglycemia always have depression, necessarily. Correlation does not necessarily imply causation.
I don't know where you got these figure from, but some authors show that about 11% of US citizens have diabetes II in 2009 Source
It is true that not all hypoglycemic people are depressed, but after more than 30 years experience working in psychonutritional medicine I have found that vast majority of depressed people - and for that matter other clients with mood disorders - were found to be hypoglycemic following a four-hour Glucose Tolerance Test.
Also take note that although a GTT may be negative, a person could still have all the symptoms of hypoglycemia as explained in Type 6 Hypoglycemia.
It must be emphasized that hypoglycemia is not the only factor in mood disorders, but that there are many other silent diseases that account for mood disorders. See:
Silent Diseases and Mood Disorders
Please also have a look at: Various references for mood orders and nutrition
About 25% of US adults have a mental illness Source
Journal of Orthomolecular Medicine showing 82 studies that link hypoglycemia (insulin resistance) with depression.... here.
Here are some studies that show an association between depression and insulin resistance source
In his studies of twelve hundred hypoglycemic patients, Stephen Gyland, M.D., found that 86 percent were depressed Gyland
Psychonutritional therapy departs from the conventional approach to the treatment of mood disorders in that it FIRSTLY assesses and treats biological factors and then later on will take "psycho-socilal factors" into consideration if at all necessary.