This is the final in the How Australians Die series that focuses on the country’s top five causes of death and how we can drive down rates of these illnesses. Previous series articles were on heart diseases and stroke, cancers, dementia and chronic lower respiratory diseases.

Diabetes is rapidly emerging as a leading cause of death among Australians. It is also a leading cause of heart attacks, strokes, amputations, kidney failure, depression, dementia and severe infections – all of which themselves contribute to premature death.

It never used to be this way. Thirty years ago, around 250,000 Australians had diabetes. Today that figure is around two million.

Around the world in 2013, more than five million people between the ages of 20 and 79 died from diabetes, accounting for 8.4% of deaths among people in this age group. This translates to one death due to diabetes every six seconds. Tragically, nearly half of these were in people under 60.

These figures likely underestimate the major role of diabetes in death as it frequently goes unreported as a cause of death. One study showed that only 35% to 40% of people with diabetes who died had the disease listed on their death certificate, while only about 10% to 15% had diabetes listed as the underlying cause of death.

Which type of diabetes is worst?

Diabetes is characterised by higher than normal levels of glucose in the blood, caused by having insufficient insulin production or function to keep glucose levels under control.

This can come about if the immune system inadvertently destroys the insulin producing cells of the pancreas. This is called type 1 diabetes. It can occur at any age, but is most common in children and young adults.

Ectopic fat – fat that accumulates outside the typical stores underneath your skin – can also reduce insulin production and cause resistance to its glucose lowering effects. This is called type 2 diabetes and accounts for 95% of all diabetes cases. It can occur at any age, but is most common in older adults.

Because of its substantially higher frequency and the older age of its sufferers, type 2 diabetes kills many more people than type 1 . However, both kinds of diabetes can shorten lives.

For example, the life expectancy of someone with type 1 diabetes in Australia is 12 years less than observed in the general population.

Equally, a man in his fifties with type 2 diabetes is twice as likely to die in the next five years than one without diabetes.

Deaths due to diabetes are substantially higher in some settings and populations. For instance, the impact of diabetes on mortality may be at least five times higher in Aboriginal and Torres Strait Islander people as in non-Indigenous Australians.

Pre-diabetes

On average, the higher the blood glucose, the greater the risk from complications of diabetes and premature mortality. Consequently, lowering glucose levels is an essential component of diabetes care and can substantially improve the survival of people with diabetes in the long term.

However, the lack of success in short to medium-term studies shows the long shadow of diabetic complications and the importance of both early identification and long-term treatment.

One in five Australians have moderately high glucose levels; not high enough to be called diabetic but still enough to increase their risk of dying too soon. This is called pre-diabetes and well over 60% of these people will ultimately develop diabetes without intervention.

Because there are many more people with pre-diabetes than have diabetes, it has been estimated that most deaths due to elevated blood glucose levels actually don’t occur in people with diabetes. Such data further suggests the true ranking of elevated blood glucose levels as a cause of death in Australians is likely much higher than number five.

Changing causes of death in diabetes

Diabetes has always been a killer. In the second century AD, Greek physician Aretaeus of Cappadocia described diabetes mellitus as a rare but fatal disease characterised by “the wasting of flesh and limbs into urine”.

Modern diabetes treatment has now abolished the idea of emaciation caused by the excessive loss of glucose into the urine. In its place, diabetes has transformed into a wholly different kind of killer.

Heart disease and stroke account for about a third of deaths in people with diabetes. Consequently, reducing risk factors for heart disease – including cholesterol and blood pressure levels, stopping smoking, dietary change, increasing physical activity and weight reduction – are cornerstones of diabetes care.

There is evidence that improvements in the management of diabetes have led to a substantial reduction in the frequency of deaths from heart disease and strokes over the past 30 years. Unfortunately, the rising prevalence of diabetes has outstripped much of these gains, the result of which is that diabetes is now the leading cause of heart disease in many countries, including Australia.

With the decline of deaths due to heart disease, cancer has now emerged as the leading cause of death in Australians with diabetes. Indeed, diabetes is now considered an important risk factor for many cancers such as liver, pancreatic, endometrial, colon, breast, and bladder cancers.

Where to from here?

At least two out of every five adults will develop type 2 diabetes in their lifetime. Yet it is preventable and may even be reversible in its earliest stages.

It is clear that simple measures, such as improving diet, weight loss and regular physical activity, can have profound and ongoing effects to not only reduce the risk of developing type 2 diabetes, but also subsequent mortality.

Given the importance of diabetes, it is up to every person, society and country to recognise the disease as a major threat to well-being and actively take opportunities for diabetes prevention or face an overwhelming health crisis. Here in Australia, the recently released National Diabetes Strategy outlines many of the first steps needed.

Merlin Thomas receives funding from NHMRC and JDRF

Paul Zimmet does not work for, consult, own shares in or receive funding from any company or organization that would benefit from this article, and has disclosed no relevant affiliations beyond the academic appointment above.