Diane Abbott has returned to her role of shadow home secretary after diabetes forced her to miss the end of the general election campaign.
Labour leader Jeremy Corbyn said his close ally was back in the shadow cabinet after suffering “a great deal”.
Ms Abbott was briefly replaced by Lyn Brown and later revealed she had been diagnosed with the condition in 2015.
Mr Corbyn told ITV’s Peston on Sunday she was “getting all the support necessary”.
During the election campaign, Ms Abbott faced criticism for her performance after she stumbled several times during interviews and appeared unable to give detailed answers.
In one interview with LBC Radio, she mistakenly said plans to boost police numbers by 10,000 would cost £300,000. It led to a barrage of criticism from the Conservatives who said she could not “add up”.
She also pulled out of an interview with BBC’s Woman’s Hour with just a few minutes’ notice as unconfirmed reports circulated that some in the party leadership had lost confidence in her.
Just 48 hours before polling day, Labour said Ms Abbott was taking a period of sick leave and would be replaced “indefinitely” by Lyn Brown.
After the election she told the Guardian her condition was “out of control” during the campaign.
The Hackney North and Stoke Newington MP, who increased her majority in the June 8 election, said she struggled after facing six or seven interviews in a row without eating enough food – vital to managing her blood sugar levels.
Mr Corbyn said: “Diane suffers from type 2 diabetes and suffered a great deal during the latter part of the election campaign.
“I had a chat with her during that period and we felt that it was right that she took a break from intensive campaigning at a national level.”