Diane Keaton's Last Instagram Post Is Heartbreaking Now Diane Keaton's death at age 79 left film buffs and fans devastated. The iconic actor seemingly had no health issues prior to her passing, and the news came as a shock to many. She appeared to be happy and healthy in her last Instagram post on April 11, smiling widely while posing with her adorable golden retriever in honor of National Pet Day. There was no sign of the heartbreak to come. It wasn't just her millions of devotees who were blindsided by Keaton's unexpected death. According to a close friend, her health had taken a sharp turn for the worse just months prior, and proceeded to decline rapidly. "It was so unexpected, especially for someone with such strength and spirit," a source told People on October 11, adding that she'd kept her difficulties a secret from those outside of her inner circle. "In her final months, she was surrounded only by her closest family, who chose to keep things very private," they shared.