Researchers have published the first reliable evidence of the prevalence of diabetes and prediabetes in New Zealand. The number of people with diabetes is likely to rise significantly in future years unless effective prevention strategies are introduced. Caroline Wood reports.
Lead researcher Dr Kirsten Coppell, Edgar National Centre for Diabetes and Obesity Research
The number of people with diabetes is high and rising in New Zealand - and this should sound alarm bells for policy makers and health providers.
This is the stark message to come from a landmark University of Otago study, which provides the first evidence-based figures for the number of people with diabetes and prediabetes in the general population.
Seven per cent of New Zealanders have diabetes and a further one in five face the prospect of getting the condition in the future, according to the study, which was published in the New Zealand Medical Journal in March.
Worryingly only half of the younger adults with diabetes in the study knew they had diabetes - for every participant under 45 years with diagnosed diabetes, there was another person who was undiagnosed.
Diabetes was the sixth leading cause of death for all New Zealanders in 2009 and the fourth leading cause of death for Maori. Health costs for treating diabetes are rising in line with the increasing number of people being diagnosed.
The true burden of diabetes has historically been under-estimated in New Zealand because no-one knows exactly how many people have diabetes - diagnosed or undiagnosed. Estimates have previously been based on assumptions and modelling and haven't been very reliable.
To try to plug the knowledge gap, researchers from the University of Otago analysed thousands of blood samples collected from participants in the 2008/09 Adult Nutrition Survey. They checked the HbAlc levels of each participant.
Dr Kirsten Coppell, Professor Jim Mann, and colleagues from the university's Edgar National Centre for Diabetes and Obesity Research, were able to see how many respondents had diabetes (diagnosed or undiagnosed). They were also able to check the samples for prediabetes, an important predictor for future diabetes rates.
"These data, when compared with the first measurement taken in 1967, provide convincing evidence that the prevalence of diabetes in New Zealand has increased over time," says lead author Dr Kirsten Coppell.
"It provides for the first time reliable estimates of diabetes and prediabetes prevalence in New Zealand."
She said the number of people with prediabetes, on top of an already high prevalence of diabetes in the general population, should be of major concern to policy makers. People with prediabetes have glucose levels above the normal range but have not yet gone on to develop full-blown diabetes.
The study found an 'alarmingly' high number of working age adults had prediabetes (see table left). The 7.5 year probability of these people developing type 2 diabetes is 41 per cent. The risks are even higher for those who are overweight, have high blood pressure or cholesterol.
"The implications of increased diabetes-related morbidity, mortality and health care costs are considerable," Dr Coppell added.
"Implementation of effective, evidence-based diabetes prevention studies is urgently required to reduce the increasing cost of the diabetes epidemic."
Dr Coppell and colleagues hope to attract funding for further research into the effectiveness of dietary intervention at GP level for those with prediabetes.
Key study findings
- Seven per cent of the population has diabetes and one in five adults are at risk of getting it.
- The number of people with diabetes has risen over time since 1967, when figures were first recorded - study confirms this for the first time.
- The level of undiagnosed diabetes is worryingly high among younger (working age) adults. Only half of those adults under 45 knew they had diabetes.
- Prediabetes is high among Pacific (24 per cent) and Maori (20 per cent).
- Effective evidence-based prevention strategies are urgently needed to stem the diabetes tide.
Research confirms worrying levels of diabetes
|NZ adults aged 15 years and over|
|Overall diabetes prevalence||7%|
|Pacific - prediabetes||24%|
|Maori - diabetes||10%|
|Maori - prediabetes||20%|
|Prediabetes (35-44 age group)||20%|
|Prediabetes (45-54 age group)||25%|
|Prediabetes (55-64 age group)||45%|
Why don't we know how many New Zealanders have diabetes?
It is not known exactly how many people have diabetes in New Zealand. There has been a lack of reliable data on the prevalence of the condition amongadults and children.
The Government's Virtual Diabetes Registry, established 10 years ago, provides some limited data. It counts people with diabetes by analysing six national databases (hospital admissions, attendance at diabetes outpatients
or retinal screening, diabetesmedication, HbAlc testing and mortality). It doesn't capture people with undiagnosed diabetes, or prediabetes, nor does it distinguish between those with type 1 or type 2 diabetes.
The four national health surveys undertaken since1992 include self reports of doctor-diagnosed diabetes - but do not capture people who are undiagnosed, or those with prediabetes.
The University of Otago research using blood samples from the 2008/09 Adult Nutrition Survey, allowed researchers to collect reliable data on the rate ofdiagnosed and undiagnosed diabetes, as well as prediabetes, among a representative sample of New Zealand's population.
From Diabetes New Zealand Magazine - Winter 2013