Diane

Diane is Sheldon's therapist.

History
Sheldon was seeing Diane while Sarah Nelson was missing. She was concerned because of his focus on Nick Calhoun and why Nick wasn't seeing him anymore. She also forced him to confront his cancer and treatment options.

After Nick came to see him saying he had met a woman, Sheldon discussed his doubt with Diane, who believed Sheldon was off the mark.

When Sheldon told her he'd turned down a lunch offer from Miranda, he said it was because their relationship didn't go outside that room, but she said it was already outside that room, which he knew. He said she's terminal. He rejected the idea that he was like Laura, who'd left him when she found out he had cancer. He admitted he was afraid.

Career
She is a therapist.