Type 1 Diabetes Life Expectancy Still 12 Years Short of Norm

Marcia Frellick

April 07, 2016

Two large new studies have found that, although there have been life-expectancy gains for people with type 1 diabetes, similar gains have been seen in the general population, thus failing to narrow a gap that stands at nearly 12 years.

Both studies were published online in Diabetologia, one detailing findings from Australia and the other from Sweden over the past 2 decades.

The two sets of authors both conclude that a multipronged approach is required to improve life expectancy for those with type 1 diabetes, including better glycemic control, as well as more focus on preventing chronic cardiovascular disease in these patients, who are at high risk of the latter. This should include more concentration on smoking cessation and better lipid management.

Penning a commentary that discusses both studies, Lars Stene, PhD, of the Norwegian Institute of Public Health, Oslo, says these two "impressively large population-based registries" have "documented a [life-expectancy] gap [in type 1 diabetes] compared with the general population that has…remained largely unchanged since the turn of the millennium."

The two papers fill "some knowledge gaps," he notes, "but others remain."

Australian Findings Broadly Generalizable, Similar to Swedish Ones

In the first study, Lili Huo of the Baker IDI Heart and Diabetes Institute, in Melbourne, Australia, and colleagues derived mortality rates of Australians with type 1 diabetes listed on the National Diabetes Services Scheme (NDSS) between 1997 and 2010 (n = 85,547) by linking them to the National Death Index.

Because the contemporary study was nationwide, authors said the results likely would translate to similar Western countries.

A total of 5981 deaths were found among the type 1 diabetes patients during the 902,136 person-years of follow-up.

While life expectancy in 2004–2010 improved for those with type 1 diabetes compared with 1997–2003, it also increased in the general population, and therefore the gap didn't close.

They found that Australian type 1 diabetic patients had an estimated loss in life expectancy at birth of 12.2 years compared with the general population (11.6 years less for men and 12.5 years less for women.)

For type 1 patients, estimated life expectancy at birth was 66.7 (men) and 70.9 years for women.

"We observed marked reductions in life expectancy across all age intervals, even in the very old, as compared with the general population," the authors write.

Death from endocrine and metabolic disease was the major factor in lost years between the ages of 10 and 39 years — this reduced with advancing age, while the contribution of deaths from circulatory disease increased as people got older.

"For improvements in life expectancy, greater attention must therefore be paid to both the acute metabolic and chronic cardiovascular complications of type 1 diabetes. A failure to address either one will continue to leave type 1 diabetic patients at risk of premature mortality," the authors write.

Similar Findings in Swedish Population

The second study, by Dennis Petrie, PhD, University of Melbourne in Australia, and colleagues, found similar results after analyzing health records from the Swedish National Diabetes Register (NDR), which were then linked with death records.

For men with type 1 diabetes, the life expectancy at age 20 increased significantly from 47.7 years in 2002–2006 to 49.7 years in 2007–2011, but life expectancy in the general population saw a similar gain. The gains were largely due to a reduction in cardiovascular deaths, the study finds.

Their female counterparts saw no significant change, with a life expectancy at age 20 of 51.7 years in 2002–2006 and 51.9 years in 2007–2011.

Therefore, just as in Australia, the life-expectancy gap between patients with type 1 diabetes and the general population has not changed much over recent decades and remained at 10 to 11 years for men and 11 to 12 years for women, according to the study.

The authors conclude that care for those with type 1 diabetes must improve to close the gap, noting that a significant portion of patients have poorly controlled HbA1c levels.

"In addition," they write, "with 10% of men and 13% of women still reported as current smokers in 2011, additional smoking-cessation programs could generate further improvements. While there have been large increases in the use of lipid-lowering medication, further expansion could generate additional gains, given this population's high underlying CVD risk."

More Info Needed on Life Expectancy for Type 1 Diagnosed Later in Life

In his commentary, Dr Stene says that even with these large new studies and previous work, there is still a lack of data on life expectancy for those diagnosed with type 1 diabetes at 50 years and older. This comes from the difficulty in determining whether diabetes is type 1 or 2 in older populations, he said.

"In the studies presented in this issue, patients had to be <30 years [Swedish cohort] or <45 years [Australian cohort] at diagnosis. This means that all observed mortality in the oldest age groups was based on patients who had to survive for decades after diagnosis to contribute to the studies," Dr Stene notes.

"We still do not know anything about the mortality or survival in the first years after diagnosis of type 1 diabetes in those diagnosed in the highest age groups."

The Petrie et al study was supported in part by the National Health and Medical Research Council (NHMRC) and the Australian Research Council's Discovery Early Career Awards funding program. The authors report no relevant financial relationships. The Huo et al study was funded by the NHMRC and the Australian Government Department of Health and Ageing and partly supported by the Victorian Operational Infrastructure Program scheme. Dr Huo is supported by China Scholarship Council. Disclosures for the coauthors are listed in the article. Dr Stene is supported by the Research Council of Norway.

Diabetologia. Published online January 21 and April 5, 2016. Huo et al article, Petrie et al article, Editorial

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