Public health

Fewer complications in people with type 2 diabetes, but gaps persist

Cardiovascular complications are decreasing among Australians with type 2 diabetes but disparities remain in mortality compared to people without diabetes, new figures from WA show.

A study of complication rates among people enrolled in the Fremantle Diabetes Study also shows the excess rates of end-stage kidney disease in people with T2D appear to have worsened over the last two decades, despite improvements in treatment.

The findings come from an analysis of changes in complications and mortality rates in the 15 years separating the first phase of the Fremantle Diabetes Study (1993-96)  and the second phase (2008-2011).

Researchers calculated five-year incidence rates for complications in 1291 participants with T2D from phase 1 and 1509 patients from phase 2 and compared these with rates for control groups of 5159 and 6036 patients without diabetes, respectively.

For myocardial infarction (MI), incidence rates declined by 39% in patients with T2D and by 20% in patients without T2D.

For stroke there was a 45% reduction among patients with T2D but no change in patients without diabetes.

Patients with T2D also showed greater decreases in incidence rates of heart failure (38% vs 30%) and cardiovascular disease mortality (63% vs 51%).

However despite decreases in mortality and increases in overall survival rates among all patient groups, a significant difference in mortality rates remained between people with and without diabetes.

End stage kidney disease incidence increased six-fold in the T2D patients and four-fold in the group without diabetes.

At baseline, the combined cohorts had a mean age of 65 years and 50% were male.

Study author Dr Wendy Davis (PhD) an epidemiologist and Research Associate Professor at the University of Western Australia, told the limbic that intensification of cardiovascular risk factor management, in particular statin therapy, had likely reduced cardiovascular mortality dramatically and increased overall survival in those with and without type 2 diabetes.

“However, although people with and without type 2 diabetes are living longer, the gap in all-cause mortality between these groups persists,” she noted.

“This may be due to the common soil hypothesis, whereby people who have type 2 diabetes have historical risk factors that also predispose them to other chronic conditions such as cancer and respiratory disease and, with the competing risk of CVD death diminishing, those with type 2 diabetes are dying prematurely from these other causes instead.

Dr Davis said there had been a huge increase in the numbers being treated for end-stage kidney disease due to longer survival and greater willingness to treat and be treated at older ages than before, and this has resource and equity implications.

“Thus in addition to continuing to intensively manage CVD risk factors and glycaemia, we need to focus on preventing kidney disease,” she said.

“The management of type 2 diabetes has intensified significantly between the Fremantle Diabetes Study phases with significant benefits in terms of CVD outcomes and mortality, but more needs to be done to prevent type 2 diabetes in the first place at a population level and prevention of kidney disease needs to be prioritised,” she concluded.

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