The 29-year-old sock designer was admitted to a medical facility in Hidden Hills, California on Wednesday (28.12.16), where he was treated for complications related to his Type 2 diabetes.
According to PEOPLE: "Rob wasn't feeling well and recognised that his symptoms were diabetes-related.
"Rob has made some changes to his lifestyle, but all the latest drama with Blac Chyna has made him depressed. And he has been on a terrible diet.
"He hasn't been taking care of himself, and that's why he's now sick again."
TMZ reported that Rob had gained an "alarmingly large amount of weight after excessively eating" due to arguments with his fiancée Blac Chyna.
However, the morning after he was admitted to hospital, Rob was well enough to be released by medical staff.
The engaged pair - who have their own reality show 'Rob & Chyna' - separated earlier this month after constantly fighting with one another, but reconciled just before Christmas to spend the holiday with their newborn daughter Dream.
However, it was later claimed Chyna had been left off the guest list for Rob's mother Kris Jenner's annual Christmas bash as the family "can't stand" the constant arguments between the new parents.
An insider said at the time: "Rob's family is over Chyna. She is not invited to Kris' holiday party.
"Rob's family is trying to distance themselves from Chyna. They can't stand the toxic relationship. They very much care about baby Dream though. It's just come to the point when they think Rob is better off without being in a relationship with Chyna."