The French electronic dance music star always empathised with tragic Avicii when it became clear he was struggling with the demands of success, leading him to lose weight and battle illness, but there was nothing he could do or say to stop the Swedish musician from taking his life in April, 2018.
Guetta, who organised a Thursday night (December 05) tribute to his pal in his native Stockholm, tells Rolling Stone magazine he was trying to reach Avicii when he learned he had committed suicide.
"His manager called me and said, 'I don't know what to do anymore. It's a bit out of control'," David recalls. "I offered anything I could do or we could meet and talk. I texted him (Avicii), but it was difficult to communicate at that time."
Avicii was often dubbed the new David Guetta by EDM experts and the two DJs became close while hanging out together in Ibiza as the Swede's career was taking off.
The French star tells the publication his young pal was "a nice, introverted, humble guy", who really struggled with the demands of travelling to big DJ gigs.
"It's the pressure of maintaining success, the non-stop touring and jetlag," Guetta says. "I remember a conversation, because I was in the business for more years, telling him and his manager, 'Guys, you need to be careful - you're doing too many shows. Of course it's fun, but it's going to come back at you'."
"You push yourself constantly and it never stops. Rock bands, even pop bands, take a year to make an album and do promo and then do a tour and take a year off. We do everything at the same time. We do production on tour. We do interviews. You always need to deliver constantly. It's very difficult and the expectations, when you've reached the top, are huge, and so many people depend on you."
"We all feel the same, but you can't complain to your friends or family, because people are like, 'Are you crazy? You make crazy money and you are having a fun life. Are you complaining about that...?' We are always in the places where the party is. People go there, spend two weeks and then go back to a normal life, whereas this is the entire year for us."
Before Avicii's death, Guetta started cutting back on his concert and club commitments after seeing how ill the demands were making his friend: "It was hard for me to pretend like everything was normal and good, you know?" he explains. "He lost so much weight at some point of his life. He had problems with his stomach and then he couldn't eat. He was so skinny and already sick."
"There were cycles. I remember a moment when he was super happy and going to the gym. But there were also super difficult moments... Tim (Avicii) had a problem. We all knew there was a problem. I could see he wasn't happy. So it's not like it came out of nowhere. But it made me a little mad, to be honest, because it's almost like you could see it coming."
In the aftermath of the DJ's death, which Guetta calls "a wakeup call for our community", he drastically cut back on his own touring and now plays about 100 shows a year, down from 180.
Thursday's tribute gig at the Friends Arena in Stockholm, which benefits mental health and suicide prevention organisations, featured fellow DJs and singers who worked with Avicii, including Adam Lambert, Rita Ora, and Aloe Blacc.
The gig was live-streamed on Avicii's YouTube channel.