Over the past 20 years, strides have been made in reducing cardiovascular disease among individuals with diabetes, yet challenges persist in Denmark. Despite increased lifespans, new research indicates that people with diabetes still face higher mortality rates than people without diabetes in Denmark, with women experiencing a growing gap. The study highlights cancer as a leading cause of death from 2002 to 2019, surpassing cardiovascular disease. Researchers urge a focus on cancer risks and sex-specific strategies to address these persistent disparities.
The last two decades have seen major strides in curbing cardiovascular disease among people with diabetes, which is cause for celebration. But healthcare providers in Denmark cannot rest on their laurels just yet, says Tinne Laurberg, a researcher at Steno Diabetes Center Aarhus.
People with diabetes still have considerable excess mortality, meaning that they are more likely to die than people of the same age without diabetes, according to new research published in The Lancet Regional Health.
The new study demonstrates that, although lifespans have increased across the board, healthcare has not been able to reduce the excess mortality among people with diabetes in Denmark over the past 20 years. And for women with diabetes, the gap between them and other women is actually increasing.
Laurberg suggests that it is time to refocus on the new leading cause of death for people with diabetes: cancer.
“My impression when I talk to healthcare professionals and people with type 2 diabetes is that nobody is aware that they have an increased risk of developing” – and dying from – “cancer,” Laurberg says.
Ranking the risks
To understand how effective current treatments for diabetes are over the course of a lifetime, researchers look for evidence of excess mortality – a difference in the rate of death for a specific population group compared with what they would expect for people that age in the general population.
Advances in health overall have led to increasing lifespans over the past 20 years. This rising tide lifts all boats – including those of people with diabetes. But has it been enough to reduce the difference? Laurberg and her team set out to assess how the causes of death for people with diabetes have shifted over the past two decades in Denmark.
Denmark’s healthcare system maintains extensive records that document each person’s interaction with a doctor from birth through death. This is a rare opportunity for population researchers to work with a nearly complete data set, Laurberg explains. “The sample size is pretty much the whole country,” she says.
The scientists gathered data on all adults with diabetes in Denmark from 2002 to 2019, of whom 156,450 died during that period. These were classified into six categories according to the primary cause of death reported on the death certificate: diabetes, cardiovascular disease, cancer, cancer associated with obesity, respiratory disease, dementia and “other”.
Laurberg and her team then ranked the leading causes of death for people with diabetes in Denmark by age. Next, they compared these figures to the causes of death for the 801,828 people without diabetes who died in the same time span.
Cardiovascular gains and the ultimate 100% risk
First, the good news: the people with diabetes are far less likely to die from cardiovascular disease than they were 20 years ago. For men, the rate has halved.
Although pinpointing exactly which interventions have driven these numbers down is impossible, this is a sign that Denmark “must have been doing something very good” in managing the cardiovascular risk of diabetes.
“As soon as you get diagnosed with type 2 diabetes, almost everyone is prescribed cholesterol-lowering drugs, lipid-lowering drugs, statins,” Laurberg says. “There has been a huge effort to lower blood pressure as well.”
But even with lifespans lengthening, “we all have to die from something eventually,” Laurberg explains. This means that as fewer people die from cardiovascular disease, other causes of death increase since the risk of death is, ultimately, 100%.
One cause of death climbing the ranks in Denmark for people with diabetes is dementia. People with diabetes who might have died from a heart attack at 60 years in previous decades are now living long enough to develop, and eventually succumb to, dementia. “We expect in the future that this trend will continue,” Laurberg says. “Dementia is the only cause of death that is increasing among people both with and without type 2 diabetes.”
Laurberg and her team found that as cardiovascular deaths wane, cancer has taken over as the leading cause of death for people with diabetes. She makes special note of a rise in cancer associated with obesity.
Several types of cancer share risk factors with diabetes, meaning that they often occur together, Laurberg says. For example, people with overweight are more likely to develop both pancreatic cancer and diabetes. Other shared risk factors can include age, sex and race.
In addition, some researchers suggest that certain physical changes to the body associated with diabetes may create a more hospitable environment for cancer to develop – high blood sugar could help to feed energy-hungry tumours or changes in blood vessels may support tumour growth.
The more things change, the more they stay the same
Laurberg hopes that her findings will increase awareness of the relationship between cancer and diabetes among both healthcare providers and patients in Denmark.
Such striking advances have been made in reducing cardiovascular deaths that as long as clinicians “continue protective measures for cardiovascular disease, cancer is what they should worry about.”
“We are expecting a lot more people with both cancer and type 2 diabetes – the incidence for both is increasing,” Laurberg says. Realising that cancer is the leading cause of death for people with diabetes in Denmark should inspire additional research into how the two conditions intersect, since currently “we do not know whether treatment for cancer should differ for people with diabetes”.
Laurberg adds that the most frustrating finding is what has stayed the same over the past 20 years. Even with the important advances in healthcare, excess mortality has not budged for people with diabetes, staying the same for men and actually increasing for women.
The risk of death from cardiovascular disease has declined for women with diabetes, but the risk of all other causes of death has increased by 6–17% each decade. “This is disappointing” but clarifies that a sex-specific approach will be essential to tackling Denmark’s excess mortality for people with diabetes, Laurberg says.
