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One in five Maori may have diabetes or its fore-runner without knowing it, and the number is likely to be even higher for those who are poorer, says a study.
Researchers for Te Wai o Rona: Diabetes Prevention Strategy tested 4,269 Maori aged 28 and older from the Waikato and Lakes areas over three years.
They found one in five had diabetes or problems processing glucose - a sign diabetes may be about to develop - including one in 10 women aged between 28 and 40.
Women of that age group are a concern because they might get pregnant without knowing they have the disease, which could harm their baby.
AUT nutrition professor Elaine Rush, one of three authors of the study, said Maori women who were thinking about getting pregnant should consider a diabetes check to help avoid passing on the disease.
Babies of women with diabetes had a four times greater risk of developing diabetes, as well as a range of other health problems, she said. "That means life-long problems for those children."
For the study, volunteers fasted overnight, then were given two blood glucose tests two hours apart. In between the tests, they drank sugary water to see how their bodies would react. Of the one in five who had diabetes-related problems, one in 20 had undiagnosed diabetes and the rest had pre-diabetes.
Dr Rush said the results might be skewed by people coming to be tested because they were concerned they might have diabetes. None of the volunteers knew they had diabetes before the test, but almost two-thirds said they had a whanau member with diabetes.
Maori who had a community services card were more likely to have diabetes, a finding Dr Rush believes is connected to the eating patterns of people who live in poverty. "White bread is cheaper, full fat milk is cheaper than trim milk," she said.
Researchers believe the study group was the largest number of Maori ever tested for diabetes. The co-chair of the study's stewardship committee, Timi Te Heuheu, said the results would be used to support long-term projects that benefited Maori.
Diabetes New Zealand president Mike Smith said the figures fitted what was already known about diabetes. He said the high number of Maori with type 2 diabetes was a concern, but there were some very good community prevention programmes. Ngati Porou's joint programme with the Edgar National Centre for Diabetes Research, Ngati and Healthy, had been very successful for east coast Maori, he said.
Diabetes NZ believes about 500,000 New Zealanders have pre-diabetes and 270,000 are believed to have type 2 diabetes, some of whom are undiagnosed.
Dr Rush said the study showed how important it was for those with a family member with diabetes to be tested. She said "just a couple of bouts" of exercise a week could prevent or reverse diabetes - but only if the disease was caught early.