Helen Clark is reflecting on her time at the United Nations, as she prepares to step down next month.

The former Prime Minister has headed the UN development programme since 2009, overseeing efforts to reduce poverty and inequality.

The latest UN report shows that while people now live longer and more children go to school than 25 years ago, there's still work to be done.

However, around 800 million people go to bed hungry each night, and 11 children under five die every minute, Clark told Rachel Smalley.

Minority groups are the most vulnerable, with women in developing countries hit particularly hard.

"Rural populations with people with disabilities, ethnic minorities, indigenous people, older people, LGBTI... there are whole clusters of people that don't do as well as others."

Changes in social policy can have a huge impact, she said.

"I know that, in the time of my government, when Working for Families came in, it actually did have an impact on diminishing inequality."

Clark said that women, minorities and people with disabilities are some of the most marginalised.

She said she has no intention of slowing down after finishing.

Clark also took the chance to wish John Key well, as he prepares to leave Parliament today.

"There's definitely life beyond being Prime Minister, and I truly wish John all the best in whatever direction it takes him.

"I can't see him hanging up his boots either so I expect we will see him pretty busy and engaged somewhere, sometime."

LISTEN ABOVE AS HELEN CLARK SPEAKS WITH RACHEL SMALLEY