The MP, who will host a public meeting about health in Dunedin tonight, was commenting on Labour's election promise announced in Dunedin recently about a national cancer screening programme.
Mr Hague, who could be minister of health in a Labour-Green government, supports Health Minister Tony Ryall's approach, a four-year bowel screening pilot whose results will be assessed at conclusion.
Some patient advocates oppose the long lead-in time, but Mr Hague said it was needed to ensure any screening programme was based on scientific evidence, and supported by an adequate workforce.
He likened the promise to National's intervention in Pharmac's processes several years ago to ensure breast cancer drug Herceptin was funded.
''I was disappointed in Labour. They were announcing that policy because they thought it would be popular, rather than because they know it's the right thing to do.
''You have to be really careful with screening. There's always a superficial appeal about the fact that you will pick up cases that otherwise wouldn't have been picked up.''
The system was not providing enough colonoscopies now, and a screening programme greatly increased demand for colonoscopy.
Mr Hague reserves his strongest criticism for Mr Ryall, who he says has not addressed the type-2 diabetes epidemic, instead focusing too much on short-term surgery targets.
The cost of treating diabetes would reach $2 billion annually by 2021, he said, four times its current cost.
Mr Hague, who acknowledges he would ''love to be'' health minister if possible, believes New Zealand needs to have a public debate about how health is funded long-term.
Prevention was key to reducing spending, and rationing of care played a part. Decisions were made about rationing behind closed doors, he said, and the public needed to be involved.
The top health job held huge challenges, and the one thing that ''does keep me awake at night'' was worrying about the effect of Mr Ryall not dealing with issues such as obesity.
Mr Ryall had cut spending on health promotion, citing an unwillingness to enact ''nanny state'' measures that dictate to people.
''The price tag for that nanny state rhetoric is a massive price tag,'' Mr Hague said.
Healthy food guidelines in schools and hospitals must be restored, as a starting point for greater awareness in society, and in the food industry.
Mr Ryall was also not addressing the ''catastrophic waste of resource'' in medical and nursing training apparent in the shortage of jobs for new graduates.
It was poor planning, because New Zealand would face a serious shortfall when older workers started to retire in large numbers, he said.
Mr Hague, a former district health board chief executive, is wary of health system upheaval, and gives the Government credit for not embarking on large-scale restructuring of the system.
He also applauds Mr Ryall's announcement this week that children with profound hearing loss would be eligible for two cochlear implants, instead of one.
It was an example of the inevitable rising cost of health caused by technological advance, he said.
Asked if a drop in the dollar's value occasioned by a Green-Labour government would hit the cost of health equipment sourced overseas, he confirmed it would further pressure the budget.
''The extremely and historically unusually high New Zealand dollar has meant that we've been cushioned from quite a lot of the increased cost of that technology change.''
New Zealand needed the lower dollar for wider economic reasons, but it would be a ''shock'' for the health system.
In a press release earlier this month, Labour leader David Cunliffe said a bowel cancer screening programme was expected to prevent 180 deaths each year.
• Mr Hague will host a public meeting at 7.30pm today at Dunedin Community House.
