I am a type 2, and was diagnosed in 2008. I have dealt with depression since I was a kid, so my latest personal discovery is exciting enough that I thought I should share.
TL:DR (Too long, don't read)
I started taking L-5-methyltetrahydrofolate, a/k/a Folinic Acid. It is an OTC B12 vitamin supplement.
Back in 2008, I was put on Lexapro to get over anxiety. This was shortly after totally burning myself out (16 hour work days, 2 hours of sleep) and shortly before being diagnosed diabetic. I took myself off the Lexapro, but still dealt with the occasional, but not insignificant depressive episodes.
Fast forward to last year. A close friend was dealing with extreme treatment-resistant depression. He had gone through experimental magnetic therapy, electroconvulsive therapy, all of the standard medications, and was admitted to a psychiatric hospital. After several months of inpatient medication and ECV, he finally started taking Folinic Acid, and was released two weeks later. He hasn't had a suicidal thought since. Another patient he had befriended in the hospital had been there for years with treatment resistant depression. That patient started taking Folinic Acid and was released a few weeks later.
Fast forward to last week. During my last bout of depression, I decided to try it. I talked to my local pharmacist, and she told me there should be no side effects or contraindications with my Metformin or Prandin, so go for it. I have to tell you, I FEEL SO MUCH BETTER!
If you wish to do your own research, which I strongly encourage, google terms Folinic Acid, Leucovorin, L-5-Methyltetrahydrofolate, depression.