The new CBS sitcom, starring Annaleigh Ashford and Thomas Middleditch, was created by series vet Marco Pennette — who based its premise on his 2013 kidney transplant.

“Unlike Drew [Middleditch], I’m a diabetic, but even I was taken by surprise and didn’t see it coming,” Pennette, 54, says of his transplant. “I wasn’t really prepared for that. The doctor said, ‘You should start thinking of asking a friend to be a kidney donor.’ He said it as casually as that, and I was like, ‘What?!’

“I ended up going on a weird Easter egg hunt, asking lots of friends to coffee,” he says. “The doctor said, ‘You will be surprised who says yes and equally surprised who says no.’ And he was dead-on. Perfect strangers I didn’t really know offered [their kidney], and good friends said, ‘It’s awkward, it’s weird.’ I have one friend would wouldn’t give his kidney because he’s a swimmer — and didn’t want to deal with a scar near his Speedo.

“It doesn’t mean you’re a terrible person if you won’t donate a kidney,” he says. “But it does mean you’re a wonderful person if you do.”

“B Positive” revolves around Drew, a 35-year-old divorced dad (of a mopey teenage daughter) who, in the premiere, learns that he needs a kidney transplant — stat. He eventually finds his prospective donor in Gina (Ashford), a good-natured, hard-partying high school acquaintance. The catch? He needs to keep her off booze and drugs for three months so she can qualify to be his donor.

Pennette, whose resume includes “Mom,” “Desperate Housewives” and “Ugly Betty,” executive-produces the series with sitcom king Chuck Lorre.

“I’m really amazed at how people reach out to other people, and at a time like this it’s so important to show the character of Gina as a true angel,” says Pennette. “There are people out there who will just help other people. There could be consequences of giving a kidney, I can’t say it’s totally harmless, but I can say that my donor was standing at my bedside as I woke up and she went home the next day. And I went home the day after.

“I just want the positivity to be there, like, ‘Don’t be afraid: you can save someone’s life.’ ”

Pennette’s kidney donor was someone he knew well, though her offer was unsolicited. “She was my mom’s best friend’s daughter,” he says. “I was home for Christmas, and this woman plopped herself down on the couch next to me and said, ‘I heard about your kidney, and you’re taking mine!’ It’s weird to say this, but I knew at that moment that she meant it … then she had to lose 40 pounds so she could donate … which made her more of a miracle for me.

“There’s a speech [from Gina] in the pilot about how she was in a car accident and was supposed to be dead. She says, ‘I really believe I was saved for something, and this is it.’ I thought, ‘Who can argue with that?’ And so, in a way, my donor became a better person and I hope this changed her life for the positive. We’re still in touch and talk all the time.

“She really is a champion,” he says. “She saved my life.”

Pennette says while he had the idea for “B Positive” immediately following his transplant, it took all these years to become a reality. “It was originally called ‘B Negative’ and then I thought, ‘I’ll tell [the story] from Gina’s point of view, so let’s make it ‘B Positive,’ ” he says. “It scared me to write this. I don’t know if it was like, ‘This is my one big shot, I can’t top this so it’s got to be perfect.’

“I was working with Chuck on another idea and he didn’t seem to be enjoying it,” he says. “So I knew I had one more shot and just kind of blurted out, ‘What if we do a story about my kidney transplant and me as the recipient?’ He looked at me and said, ‘That’s a show I would watch.’ So, with that push, I went home for Thanksgiving break last year and wrote the script in a week.”

Pennette hints at how “B Positive” will progress this season.

“I think [Drew and Gina] are going to spend the first season getting toward the [kidney] surgery,” he says. “And I think Drew realizes he’s going to have to save Gina before she can save him.

“She’s as broken as he is, in a different way,” he says. “I love the idea that they’re in each other’s lives to save each other.”