At a time when most chronic diseases are showing a slowing of growth in prevalence and/or incidence, the diabetes epidemic in New Zealand continues unabated. If current trends continue, the incidence of both Type 2 and Type 1 diabetes is predicted to double in around 15 years.1,2

The rapid rise in the number of patients suffering from diabetes is consistent with environmental factors playing a major pathogenic role. The environmental factors responsible for the rise in Type 1 diabetes are elusive. In contrast, the impact of risk factors for Type 2 diabetes that are present in our current ‘obesogenic’ environment is well known, even if the best way of improving these environmental risk factors has yet to be determined. How much relevance does this epidemic have for New Zealanders?

The paper by Joshy and Simmons in this issue of the Journal argues that the cost of treating Type 2 diabetes, a potentially preventable condition, is taking health dollars away from other important conditions.3 Indeed, one estimate suggests that the annual cost of treating Type 2 diabetes will be more than 1,000 million dollars, by 2021.4

What New Zealand-specific elements form part of a local diabetes clinical epidemiologist’s job description? Epidemiology measures the determinants and distribution of disease. New Zealand has a unique ethnic mix, unique culture, and unique obligations regarding the health and welfare of its indigenous people. The impact of diabetes and its complications on Māori, in particular, has been a focus of many of the papers cited by Joshy and Simmons. These authors also highlight the impact of diabetes on Pacific Island and Asian people, living in New Zealand.

Epidemiological tools help us solve problems related to disease prevention and control, as well as help in the evaluation of health service delivery. Overseas studies have begun to address some of these issues in Type 2 diabetes; for example the impact of lifestyle intervention and therapy with metformin has been quantified in pre-diabetic populations,5 but the transferability of these ideas to the New Zealand setting is currently unknown.

Several local interventional projects have recently started, for example the Waikato’s Te Wai O Rona – Diabetes Prevention Strategy and Counties Manukau’s Lets Beat Diabetes project. These projects hope to address the question of the best lifestyle interventional approach required to prevent diabetes, from a regional perspective. Results should start to come through in the next couple of years.

The burden of Type 1 diabetes falls most heavily on the New Zealand European population. Type 1 prevalence is around 10% that of Type 2 diabetes. The mix of a relatively uncommon condition in a patient subgroup that has a genetic and environmental make up similar to that of Type 1 populations in Europe, Australia, and North America has meant that local epidemiological research in Type 1 diabetes has tended to explore points of similarity, rather than points of difference, with populations in other geographic regions. New Zealand research on the prevention and control of Type 1 diabetes is now focussed on international collaboration through the TrialNet series of studies.6

A second article in this journal, by Scott et al, examined outcomes of care in young New Zealanders with diabetes.7 Their paper highlights the importance of undertaking a nationwide approach to evaluating health service delivery in Type 1 diabetes, as they found marked regional differences in glycaemic control, which have yet to be explained. They also reached a similar conclusion to the paper by Joshy and Simmons, in their finding that young Māori and Pacific Islanders have a disproportionate burden of Type 2 diabetes and its complications.

Accurate diabetes epidemiological data that is New Zealand-specific is clearly a necessity for the development of local solutions to the Type 2 diabetes epidemic. Regional researchers have given us a snapshot of their local epidemiological findings and these findings are broadly consistent from region to region. However local clinicians and epidemiologists have struggled to find the resources required to collate accurate, up-to-date national statistics.

Robust national data is needed as a baseline against which the impact of both current initiatives, such as the free annual Get Checked diabetes check, and future national initiatives and interventions can be assessed. As an example, Budget 2006 earmarked 76.1 million dollars over 4 years to combat obesity in New Zealand. How can we know if this money has an impact on people with impaired glucose tolerance and diabetes, if we have no baseline data?

The 1996/1997 New Zealand Health Survey obtained only limited diabetes-specific data and is now 10 years out of date, yet forms the background for the only major statistical modelling undertaken of the diabetes epidemic, including the number of people suffering from diabetes in New Zealand.8

The maturing of medical information technology lead to the hope that collation of primary care statistics might provide valuable epidemiological data for chronic disease management, for example through regional and national Get Checked data.

Unfortunately Get Checked has not lived up to its promise on this count. This is partly because of lower than anticipated levels of patient recruitment but also because of our inability to give an accurate estimation of denominatory data, especially the number of Pacific Island peoples with diabetes; both points have been highlighted by Joshy and Simmons.

Obtaining accurate, relevant national data on both diabetes and impaired glucose tolerance should not, however, be beyond our reach. Looking across the Tasman to Australia, the recently completed AusDiab study is an example of a relatively low cost nationwide survey of the prevalence and risk factors for diabetes, which included an oral glucose tolerance test for all individuals surveyed who did not have known diabetes.9

In summary, the New Zealand population has a unique mix of ethnicities, resulting in a unique interaction between the environment and those individuals and population subgroups that are susceptible to Type 2 diabetes and its complications. We have energetic researchers addressing regional epidemiological questions.

A glance at the reference list accompanying Joshy and Simmons’ article shows that we also have the benefit of a history of collaboration between researchers and individual clinicians, on the few diabetes projects that have been undertaken with a national focus. Despite these advantages, we still have no clear, up-to-date idea on whether regional diabetes data really does reflect what is occurring, nationally.

Does the sum of the regional parts in this diabetes epidemiology picture accurately reflect the whole (national) situation in New Zealand? We do not know the answer to this question, even though we should. The time for a detailed national survey of diabetes is overdue.

Author information: Juliet Berkeley, Senior Registrar; Helen Lunt, Consultant Physician; Diabetes Centre, Christchurch Hospital, Christchurch

Correspondence: Helen Lunt, Diabetes Centre, Christchurch Hospital, Private Bag 4710, Christchurch. Fax: (03) 364 0171; email: Helen.Lunt@cdhb.govt.nz