Diabetes in the Torres Strait Islands of Australia: better clinical systems but significant increase in weight and other risk conditions among adults, 1999–2005

Torres Strait Islanders have the highest prevalence of type 2 diabetes in Australia, with about a third of adults affected.1 In June 1996, the Torres Strait and Northern Peninsula Area (TS&NPA) District Health Council convened a summit on diabetes that included members of each Island community, health staff and experts in the field of diabetes care and prevention. One of the five strategies proposed in the resulting “Meriba Zageth for diabetes” plan was improving the quality and scope of primary and secondary clinical care in the TS&NPA District.2 A detailed history of subsequent developments is given in Box 1.

Between 1999 and 2003, more than 300 new patients with diabetes were added to the clinic registers. In subsequent years, numbers on the registers increased, and by 2006, useful reports were being generated from the information system (Project Ferret, Pen Computer Systems, Sydney, NSW; see Box 1) for each clinic. At the same time, community-based chronic disease risk factor surveys were being undertaken in the District, and baseline results were used for service planning, including programs to improve early detection and prevention of diabetes, heart and renal disease and sexually transmitted infections.3 These surveys found extremely high crude prevalence of the metabolic syndrome (43.5% in Torres Strait Islander men and 52.9% in women, by the American National Education Program Third Adult Treatment Panel criteria).4

Here, we review (i) the current status of primary level diabetes indicators in the District and (ii) changes in metabolic risk factors in a cohort of adults without diabetes followed from 2000–01 to 2005–06. Incidence of diabetes has not previously been reported in this population.

Data from clinical records of those registered as having diabetes were extracted manually for years 1999 and 2002, then downloaded from the primary care information system for 2004 and 2005. Data quality for the latter period was checked against the clinic file in a random subsample of 100 records in the diabetes register in 2005, looking at blood pressure (BP), weight, waist circumference, glycated haemoglobin (HbA1c) level, foot check, lipid and serum creatinine levels and vaccination status. These checks found variable under-reporting on the computerised system (compared with manual files) of between 5% (HbA1c) and 40% (waist circumference). Information on insulin use was recorded in the computerised system only for Thursday Island in 2005 (for 416 patients). Where there was more than one measure recorded in a single year for a client (eg, BP or HbA1c), the most recent measure was used.

Since 1999 in the TS&NPA, there have been significant improvements in systems for early detection and case management of people with diabetes and other chronic conditions, including the introduction of a District-wide computerised primary care information system that provides population-level support for care plans, disease registers, patient recall and reports on quality of care for priority conditions. This is in line with current best practice in community level chronic care,5 although there remain problems with system and health staff support, and these require continuous attention.

The improvement in glycaemic control from a very poor baseline shown here is similar to preliminary results from other Indigenous Australian services. The “Audit and Best practice for Chronic Disease” (ABCD) project in the Northern Territory recently reported improved systems of chronic care in 12 Indigenous communities where the proportion of people with diabetes with HbA1c levels less than 7% increased from 19% at baseline to 28% by the third year.6 Also, the Quality Assurance for Aboriginal Medical Services Program reported an improvement in mean HbA1c level from 9.3% to 8.6% among 74 Aboriginal people with diabetes in two remote communities after 12 months of intensive intervention involving point-of-care testing for HbA1c with immediate client feedback and counselling.7

However, great disparities remain between reported glycaemia in Indigenous people compared with the general Australian population of people with diabetes, where 38% achieved an HbA1c level of less than 7%.8 The Indian Health Service in the United States has made significant improvements in glycaemic control (from a mean HbA1c level of 8.9% in 1995 to 7.9% in 2001) and in other intermediate clinical outcomes, resulting from increased resource allocation for quality improvement in diabetes care.9 Nonetheless, African-Americans in the US have reported levels of HbA1c about 0.65% higher than those of non-Hispanic white people with diabetes,10 although recent reports suggest that this can be improved with targeted community-level interventions. For example, in North Carolina two communities were able to show a shift in the proportion of people with diabetes with a reported HbA1c level less than 7% from 20.8% in 1997 to 44.3% in 2004. Interestingly, in this study of black Americans with predominantly low socioeconomic status, smoking rates remained unchanged at about 46%, similar to the rates we report here.11

In contrast with these improvements in community-level clinical care services, there appear to be few successful corresponding systematic interventions dealing with the causes of diabetes in the population, particularly central obesity, poor quality food and tobacco use. The incidence of diabetes in the Torres Strait that we report here is 50% higher than that reported in a cohort of Aboriginal adults from central Australia a decade ago.12 As our sample was small and only 43% of the original cohort were followed up, and as those followed up were slightly older and heavier at baseline than those who were not, our reported incidence could be an overestimate. Our study was underpowered to find an impact of tobacco smoking on risk of diabetes. In remote parts of Australia, the availability and affordability of healthy food have decreased from what was an already poor position. People in very remote areas of Queensland pay an average of $114 per fortnight more than people living in cities for a very basic family food basket, and have faced higher increases in food prices than the consumer price index, although the price of tobacco is not different from metropolitan areas.13

Tobacco smoking has been reported to have a role in incident diabetes in Japanese men14,15 (although large cohort studies have not confirmed this in European populations16) and in excess complications in established diabetes, particularly renal disease.17 The few community interventions to reduce the extremely high rates of Indigenous tobacco use in Australia that have been reported so far show modest impact,18,19 and central obesity appears to be intractable everywhere.

On the bright side, the improvements in clinical systems demonstrated here and elsewhere in Aboriginal Health Services show that major changes are possible. There is an urgent need to get whole communities to eat a healthier diet and get fitter metabolically so they can lose central adiposity and reduce blood sugar levels. In people with diabetes, for every 1% fall in HbA1c level, there can be a corresponding 38% reduction in microvascular complications,20 and it is clear that more intensive management of glycaemia (and other risk factors) is needed in this group.21 At the same time, a much higher proportion of the community has features of the metabolic syndrome. This situation demands innovative and ongoing population-level interventions which have demonstrated effectiveness and are highly cost-effective.22