The suffering is part of a wider diabetes epidemic that causes close to 1000 amputations a year in New Zealand - a loss of legs, feet and toes unknown in wealthy suburbs, but increasingly common elsewhere.
The greater burden on Māori cannot be explained by other risk factors for amputation such as deprivation and rural living. In the final of a three-part series, Nicholas Jones talks to experts about the problem and some possible solutions.
Māori are at much greater risk of losing a leg to diabetes even after factors such as deprivation are taken into account - and researchers suspect institutional racism.
A team led by Jason Gurney of the University of Otago used hospital records to track nearly 220,000 diabetics over four years. Māori were found to be at 65 per cent greater risk of above-knee amputation than Pākehā.
The result took into account other factors that could make amputation more likely, including deprivation, age, sex, rural living, prior amputation and co-morbidities (suffering other illnesses as well).
"Using the data we have, which is some of the best in the world, even after accounting for those things we are left with, this very startling problem," said Gurney, a Māori epidemiologist.
"No matter which way we slice it, we are left with a really uncomfortable reality - our system works better for some groups of people than for others."
Men with diabetes were also found to be almost 40 per cent more likely to lose a leg than women, probably reflecting a greater reluctance to seek treatment and higher rates of vascular disease and smoking.
Almost 1000 body parts will be amputated because of diabetes this year, an increase of more than 40 per cent over a decade.
Amputation is a rare complication of poorly controlled diabetes. Pain, the body's warning system, is silenced as high levels of blood sugar damage nerves, firstly in the feet and hands, the body's extremities.
Injuries go undetected, and reduced blood flow means wounds don't heal and become infected. Taking off a body part is a last resort to stop an infection becoming fatal.
Foot ulcers precede about eight in 10 diabetic amputations. Other amputations happen when tissue dies after being starved of oxygen because of restricted blood flow, a condition called ischaemia.
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Research shows more than 80 per cent of amputations are preventable, if diabetes is controlled and foot problems are detected and treated early. Patients should be fast-tracked to a specialist.
Podiatrists, for example, treat wounds, educate patients on preventing wounds and call in vascular (vein and artery) surgeons if blood flow is critically low.
Gurney said there are pockets of fantastic services, particularly in the Auckland region. However, these are "the exception to the rule".
"We know what we need to do. The literature has been clear on that for a decade - if you provide high-quality foot-care services, combined with good access to general diabetes care, you will reduce the burden.
"And we need to realise that in order to achieve that objective, we need to disproportionately invest resources towards those that need it most. Which is the bit that makes people very uncomfortable."
There's "no question" institutional racism contributes to the Māori amputation risk, Gurney said.
"People get their backs up when you start talking about institutionalised racism, but that's just suggesting our system is set up to work for some ethnicities [more] than it is for others. Which it clearly is.
"We have a system designed to suit the majority, and as a consequence the minority groups fall through the cracks."
Institutional bias means the procedures or practices of particular institutions result in some groups being advantaged.
In the health context, this could mean Māori health organisations being made to jump through more hoops for less funding, or medical advice being delivered in a culturally insensitive way, making the patient feel talked down to.
Gurney said the research didn't establish the same differences for other ethnicities including Pasifika and Asian, but the relatively small numbers could explain why. He doesn't think the difference for Māori is genetic.
"I would put my house on the fact it has very little, if anything, to do with genetics. It is a system-driven problem that is repeatable across many other international contexts, when you look at indigenous populations.
"It is a system-level problem that is, unfortunately, repeatable across a number of health contexts. I do a lot of work in cancer, and we see similar problems in terms of access to the best treatment."
Māori ethnicity was included as a risk factor when a group of leading podiatrists in 2014 developed a screening tool to help identify which diabetics were at greater risk of foot disease. That meant Māori otherwise identified as moderate risk were moved into the high-risk category, which required at least monthly podiatry visits.
Michele Garrett, podiatry professional clinical leader at the Waitematā and Auckland District Health Boards, is one of the experts who helped develop those guidelines. She says it isn't yet fully understood why Māori ethnicity is an independent risk factor.
"The disease is complex. Socio-economic factors are complex. Colonisation, there are the complexities of that.
"I don't think we fully understand why, whether it's related to maybe foot differences, shapes, how the tissue is affected. Or whether there are other confounding factors we haven't identified. But it is an area we are definitely looking at."
Increase support, and deliver it well
A big boost to public podiatry services is needed to stop amputations, one of the country's leading diabetes researchers says.
University of Otago Professor Jim Mann said podiatry access has long been "woefully lacking throughout the country, doubly so in the rural areas."
It is crucial for support to reach high-risk groups such as Māori and Pasifika, he says, and there is good work going on in that regard. For example, the Mana Tū scheme across five Auckland GP practices has special case managers assigned to work with people with poorly controlled diabetes.
By talking to the patient and seeing them in their own family environment, the case managers can identify real-life obstacles and beat them.
For instance, one woman had been told of the importance of exercise but was embarrassed to walk in her neighbourhood because of her weight. The case manager found a free bike and set it up on a rotator system, like an exercycle. She lost 50kg and now exercises outside happily.
A separate Huakina Development Trust programme holds fortnightly tikanga-based clinics at Pukekohe's Ngā Hau e Whā Marae and Ooraeroa Marae in Port Waikato.
Counties Manukau podiatrist Lawrence Kingi leads the clinics and says those attending are in an environment they know and appreciate the more informal approach. That means they aren't as likely to get discouraged about their health, and the group dynamic gives a feeling of greater support, and even a sort of competitiveness over health.
"It's like sitting in a big room. Everyone talks about their cases, and where they're at in terms of support. In GP clinics, they are quite formal, and people can feel they're not getting the support they require."
Part One: Our hidden amputation shame
Part Two: One woman's amputation horror: 'I was clawing at the walls'