The 31-year-old Keeping Up With the Kardashians star posted on her Instagram page on Tuesday a photo of herself looking, as she put it, "melancholy."
Rob, 28, who has been reclusive for more than a year, was hospitalized over the holiday weekend and diagnosed with diabetes, or elevated blood sugar, which can be life-threatening if not treated. A source told E! News on Tuesday he had returned home and is "fine," adding that his health scare was a "wake up call" and that doctors told him that he needs to lose weight, exercise and change his diet dramatically.
Rob has largely kept out of the public eye for more than a year and has been absent from the family's reality show for more than two years while battling weight gain of an estimated 100 pounds and depression.
Khloe had in mid-December shared a cryptic, moving throwback photo of her and Rob and a message, saying, "If only you could see yourself through my eyes! I'll forever be obsessed with you! My one and only! #MyAce"
She had revealed in July Rob had moved back in with her, adding she "wouldn't have it any other way."
Watch Keeping Up With the Kardashians on Jan. 3 on E! at 9/8c.