Is David LaChapelle the 21st century's Andy Warhol?

He first got into New York's most exclusive nightclub because he was pretty and holding hands with a boy. As a regular, he took cocaine and tried snorting heroin, but hated it. "I've done stuff but really never to the point of addiction or f*****g up jobs," he summarises. He met Warhol, who liked him, and whom LaChapelle cleverly stuck by until he commissioned him to shoot for his magazine, Interview.

This first New York stint was cut short when his late father, a tobacco executive, made him enrol at art school in North Carolina, a move he is deeply thankful for. On his return he began his ascent in the magazine world, while working as a wedding photographer and as an escort. "I think you call them rent boys over here," he says.

He soon became known as the photographer for whom artistic vision was everything. When American Vogue editor Anna Wintour asked him to shoot Lauren Hill and The Fugees wearing Tommy Hilfiger, he told her he'd shoot Hill on her own in Galliano. When she said no, he walked away. Not that he cared. He thinks The September Issue, the documentary shot at American Vogue, is dreadful. "Gaaad, did anyone crack a smile in that entire film?" he asks. "You don't see a second of laughter, not one molecule of it."

Instead he worked for Rolling Stone, Interview and Vanity Fair, shooting a young Paris Hilton lying in the Malibu surf, $100 bills floating around her, laughing manically, a breast exposed. He shot Lil' Kim naked, her body tattooed with the Louis Vuitton logo. He's photographed Pamela Anderson so many times, he probably knows her body better than a lover.

He's also close to aristocratic fashion muse Daphne Guinness. "Ah, she's so sweet and gentle," he says. The pair first met on a Tatler shoot in Paris 10 years ago through Blow, who took her own life three years ago. "Why did she have to be so sad, Issy?" he asks. "I really tried to get her out of London." When he got the call that their friend Alexander McQueen had also died, he rushed over to Guinness's New York apartment. "I found her crumpled in the library," he recalls. "I spent the night with her and we sat all day in her closet putting McQueen outfits together."

The flip-side to a life that radiates glamour and famous friends has been LaChapelle's struggle with bi-polar depression, a condition characterised by hyperactivity and sleeplessness, followed by crushing lows. "I was last hospitalised 18 months ago," he says. "I've finally found a doctor who understands that antidepressants don't work for me. My cure is sleep and exercise." He makes light of it all ("each time the police took me away in an ambulance I was singing, naked, but very happy"), recalling how he'd sit at the hospital window overlooking LA's Rodeo Drive, laughing at the people below. "There they were with their shopping bags and cell phones and we were like: They're the crazy ones.' I met beautiful people in hospital. If you can be happy in a mental institution, you can be happy anywhere."

Even when he sold himself for sex? "Those were different days," he says, suddenly serious. "Please make that clear. I don't want anyone to think what I did was cool. It wasn't. Most of the men had never been with another man before. I would listen to their stories, really talk to them, about things that interested them like Tennessee Williams. No one ever asked me to do anything funny. Today, you meet people over the internet. You don't know who they are — it's so dangerous."

He regularly retreats to his 20-acre farm on the Hawaiian island of Maui where his Lithuanian-born mother, who is suffering from cancer, and his sister often visit. As does his friend Lady Gaga. "She's so smart, just nice," he says. "She writes her own music and she plays the piano like nobody's business. She's Freddie Mercury come back to life."

He recently shot her for Rolling Stone even though he has generally given up magazine work. "When I ask my interns," he says, "what their favourite magazine is, they don't know what I'm talking about. Print is not the medium of the young." But what about love? He rarely speaks about his private life. "I'm very happy at the moment," he says. "I've just started seeing someone so I'm never lonely in terms of having someone to sleep with. Sex is one of the gifts of life but I'm not a promiscuous person. I love flirting and talking to someone and you know that first kiss? Aaaaahhhhh, I'm so into that." Is it different being gay now?

"It's harder because pornography has become such a commodity. I do it myself with women but I never shoot a penis. Penises are too distracting, I am trying to communicate with everyone, not make them giggle."

We've now gone into hiding from his next interview, cooped up in a narrow stairwell sitting opposite each other, legs perched on the wall like students. He is charming and sweet and even sings me a couple of lines of Michael Jackson's Speechless: "That's how you make me feel. Though I'm with you I am lost for words and nothing is for real." By the way, I ask, who was the priest, was he for real? "Yeah. He was some Church of England guy who interviewed me for my Jesus is my Homeboy show," he says, of the exhibition featuring rappers at the Last Supper.

Are you religious? "I don't want to live a life without the possibility of miracles. I have a lot of faith, I know there is something beyond this life."

I later find out the priest was Father Nicholas Cranfield, art critic of the Church Times. This is what he wrote following his first meeting with LaChapelle: "I was not sure what to expect of the artist ... but in this self-chosen project I found a deeply spiritual enquirer using his real skills to proclaim the Christian message."

How apposite of Father Nicholas to have found God, of all places, through David LaChapelle's lens.

David LaChapelle: The Rape of Africa is at Robilant + Voena, 38 Dover Street, W1, until May 25.