Complications and Mortality of Diabetes in Australia
Associate Professor Jonathan Shaw
Affiliation : International Diabetes Institute, Melbourne, Australia
Diabetes represents a growing problem in both developed and developing countries, with most of the
healthcare burden arising from diabetic complications. The recent AusDiab study provides a national popu-
lation-based sample of over 11,000 adults from the general population of Australia from which estimates of the
prevalence and impact of diabetes and its complications can be derived.
Diabetic retinopathy, which is the leading cause of visual loss in working aged people in Australia,
was found to be present in 21.9% of people with previously diagnosed type 2 diabetes. The major risk factors
for retinopathy were poor glycaemic control, hypertension and duration of diabetes, with retinopathy being
identified in 57% of those with a diabetes duration of over 20 years. Over 75% of people with type 2 diabetes
reported having an eye examination in the previous 2 years.
Peripheral arterial disease and diabetic neuropathy are the reasons that diabetes accounts for
approximately 50% of all lower limb amputations. Foot examinations undertaken in the AusDiab study
showed that these complications were each present in 13-14% of those with type 2 diabetes, and that 24.1%
of those with previously diagnosed diabetes, and 15.3% of those with newly diagnosed diabetes had at least
one significant risk factor for future foot ulceration. Only 50% of those with diabetes reported that they had
had their feet examined in the previous 12 months, and even amongst those with ‘at-risk’ feet, only 57%
reported a foot examination in the previous year.
Diabetes is now the biggest single cause of end-stage renal disease in Australia. Diabetes was the
primary renal disease for 26% of all those going onto dialysis or a renal transplant program in 2003,
compared to 16% in 1993. Over this 10 year period, the numbers of people with diabetes registered with end-
stage renal disease tripled. Within the AusDiab data, microalbuminuria was present in 25% of those with
previously diagnosed diabetes. Even after adjusting for other risk factors, those with impaired fasting glucose
and impaired glucose tolerance had a 20-40% increased risk of having microalbuminuria, compared to those
with normal glucose tolerance.
Economic data have shown significant increases in costs associated with the presence of diabetic
complications. The mean annual cost of healthcare increased from AUS$4025 in those without complications
to $7025 in those with microvascular complications, $9055 in those with macrovascular disease, and $9645
in those with both types of complications.
Mortality data published from the Dubbo Study, relating to elderly people in a single Australian
town, showed that diabetes was associated with a 60-90% increased mortality over 15 years, and that in this
elderly population, diabetes was associated with 18 months shorter survival. Data from five other Australian
and New Zealand cohorts showed that over approximately 5 years, diabetes led to an approximate doubling
of cardiovascular mortality. In the AusDiab study, mortality data show that compared to those with normal
glucose tolerance, total mortality over 4 years was increased by 40%, 70%, 60% and 140% in IGT, IFG, newly
diagnosed and previously diagnosed diabetes, respectively.
Overall, these data show the significant health burden and financial costs associated with diabetic
complications in Australia. Perhaps most concerning is the increased mortality risk associated with IGT and
IFG over only four years.
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