The 'Get Your Freak On' singer first started displaying symptoms of the condition, which is caused by an over-active thyroid, back in 2008, but only confirmed her ill-health this week.
It was subsequently reported that Elliott's recent low profile had been a direct result of her struggle with the disease, but the rap star today clarified that she hadn't allowed herself to be "slowed down".
"There have been some inaccuracies reported in regards to my diagnosis with Graves' Disease, so I wanted to clear things up," she said in statement. "I was diagnosed with Graves' Disease about three years ago but it really hasn't slowed me down at all.
"I rocked my performance on VH1 Hip Hop Honors' tribute to Timbaland last year. I've written and produced a bunch of Grammy-nominated, #1 hits for artists like Keyshia Cole, Monica and Jasmine Sullivan. I toured the UK, Europe, Asia, Africa and Australia. And on top of all that, I'm working on my new album."
She added: "I feel great. Under my doctor's supervision, I've been off medication for about a year and I'm completely managing the condition through diet and exercise."
Elliott promised last year that her imminent comeback will be "something crazy".
Watch the video for Missy Elliott's 'Get Your Freak On' below: