Thank you for answering my questions. I'm really glad for the new information, especially the piece about the diabetes. I don't think that it's a coincidence that the more severe depression has come with the diabetes diagnosis. It's not unusual for diabetics to have depression too (it's unfortunately common). This can occur for a variety of reasons, not the least of which is the stress that inevitably comes with managing the condition.
1) Dietary/glucose control will be important, as I'm sure you know. However, keeping your sugar at too low of a level can be a problem too. When blood sugar is too low it can cause depression, fatigue, and feelings of "derealization" - feeling like you're not real or outside of your body. Do you take your sugar often? If so, does it run high or low?
2) The usefulness of medications depends on enzymes in the liver. Specifically, there is an enzyme called CYP-450 that breaks down most antidepressant medications. People with diabetes sometimes have trouble breaking down the medications and more of it gets excreted without being absorbed. Having medical tests of liver function may be helpful.
3) The near panic and derealization that you're feeling could be linked to medical causes, but it could also just be a normal change over time (you mentioned that you were prone to depression, etc throughout your life). In panic or anxiety, a straight SSRI (selective serotonin reuptake inhibitor) like prozac, celexa, lexapro, etc may be better. Drugs that stimulate norepinephrine (SNRI's like Cymbalta or Effexor) can make anxiety worse. Also, a benzodiazepine like Xanax will make the derealization (the "outside looking in") feeling worse.
4) A vitamin B regimen may help with energy without causing anxiety.
5) Magnesium may help with anxiety as well
6) Stay away from herbal depression remedies like St. John's Wort, as it shouldn't be taken with diabetes meds.
I look forward to your thoughts so far...