BARCELONA, Spain — The largest and most accurate assessment of contemporary life expectancy in people with type 1 diabetes to date shows they are almost certainly living much longer than they have historically.

"It's very good news, and clearly changes in care are having an impact in driving down mortality," Helen Colhoun, MD, MFPHM, FRCP, from the diabetes epidemiology unit, University of Dundee, Scotland, told a press conference here at the European Association for the Study of Diabetes (EASD) 2013 Meeting. Her colleague, Shona Livingstone, MSc, presented the results in a poster today.

The research shows that there has been a large narrowing in the gap between remaining life expectancy at age 20 years among those with and without type 1 diabetes. But a disparity still remains, and more work is needed to further close the gap to "try to get this difference down to zero," Dr. Colhoun said.

The new analysis shows, for example, that those with type 1 diabetes are living around 11 to 14 years less, on average, at the age of 20 to 24 years than those in the general population; this figure drops to 5 to 7 years less at age 65 to 69. In the past, life expectancy has differed by as much as 27 years between those with type 1 diabetes and the general population, she pointed out.

"I'm very confident that the narrower differences we are seeing now do reflect enormous advances in the management of type 1 diabetes in the past 20 years," she said. One major contributor is undoubtedly better glycemic control, she noted, stressing nevertheless that a third of those with type 1 diabetes still don't have anywhere near good control — those patients therefore represent one obvious target group for intervention, she urged.

And attention must also be paid to many other risk factors known to affect mortality, she said, including lipids, blood pressure, and making sure diabetics never smoke or are helped to try to quit if they do.

Sigurd Lenzen, MD, from Hannover Medical School, Germany, who was not involved with this research, said the findings are not unexpected.

It has long been known that life expectancy in type 1 diabetes is significantly reduced, he told Medscape Medical News. "This study now shows, not surprisingly, that this disparity [in lifespan between type 1 diabetes patients and the general population] can be reduced, not only with optimal treatment but also when patients live in a perfect social environment."

But "this cannot abolish reduced life expectancy," since type 1 diabetes is an incurable disease, he observed. However it means "we must try to get…treatments from the experimental level to the patient as soon as possible."

David Hopkins, MBChB, from Kings College Hospital, London, United Kingdom, said: "This is a very important piece of work." Despite the improvements seen, "people with type 1 diabetes remain at significantly increased risk of death from ischemic heart disease and renal failure," he warned. "Further action on the prevention/early detection of these specific health issues is warranted to bring the healthy life expectancy of people with diabetes in line with that of the general population."

Largest-Ever Study of Life Expectancy in Type 1 Diabetes

Dr. Helen Colhoun

Dr. Colhoun said there are surprisingly few large-scale assessments of life expectancy in the historical literature, but what there are point to some evidence that this is improving for people with type 1 diabetes.

In 1975, Goodkin et al reported a 27-year difference in life expectancy between those with type 1 diabetes and the general population (J Occup Med. 1975;17:716–721). Diabetes UK currently quotes a difference of more than 20 years in life expectancy between people with type 1 diabetes and those without.

And just last year, the Pittsburgh Epidemiology of Diabetes Complications (EDC) study published data showing an increase in life expectancy of around 15 years between those participants diagnosed with type 1 diabetes in 1950–1964 vs those diagnosed in 1965–1980 (Diabetes. 2012;61:2987-2992). But there were only 500 people included in the Pittsburgh analysis, Dr. Colhoun noted, adding that her own study, assessing close to 25,000 people with type 1 diabetes, is very likely "the largest-ever study done of life expectancy in type 1 diabetes."

She and her colleagues used the nationwide Scottish Care Information — Diabetes Collaboration database, which contains electronic health records for almost all individuals with diabetes in Scotland. They used anonymous information from this to look at people living with type 1 diabetes aged 20 years or older anytime between 2008 and 2010 and then linked this with death data.

They identified 24,971 people aged 20 years or older with type 1 diabetes in this 3-year period, among whom there were 1079 deaths. For each age band, they calculated the rate of death over the study period and then compared this with figures for the general population of Scotland as a whole.

In those with type 1 diabetes, the remaining life expectancy for those aged 20 to 24 years of age was 45 extra years for a man and 47 extra years for a woman, compared with 56 and 61 years for men and women in the general population.

For type 1 diabetics aged 65 to 69 years, the remaining life expectancy was estimated at 12 years for both men and women, compared with 17 years for men and 19 years for women in the general population.

Women With Diabetes Still Most Disadvantaged

Dr. Colhoun stressed that in their calculations, her team assumed that care for diabetes is "as per current recommendations," whereas in reality it will improve as time goes on, "so these are conservative estimates," she explained.

One interesting finding is that the results show that among women there is a bigger gap between life expectancy among those with type 1 diabetes compared with the general population than is seen among men. This is despite the fact that women live longer than men.

"At all ages, the difference in life expectancy is a few years worse for women than for men, and we do need to try to understand this," Dr. Colhoun said.

One possibility is that the "worst period" for type 1 diabetics in terms of control of glycemia and other risk factors appears to be the early 20s, and it's possible that this period of instability goes on longer in females than in males, she speculated.

Glycemic Control: The "Elephant in the Room"

The observed improvements should now be reflected in differing life-insurance premiums for those with diabetes, Dr. Colhoun and her team believe, but their efforts to discover what information insurance companies are basing their calculations on has so far gone unanswered.

"Patients are often being quoted much bigger differences in life expectancy than we found, which suggests to me that older data are being used," she said.

Dr. Hopkins agrees. The significant improvements in life expectancy for people with diabetes as a result in advances in care over the past 2 decades "are not reflected in existing estimates used for actuarial purposes," he noted. "Dr. Colhoun and her team have presented robust life tables based on large-scale population data and rigorous analysis, which should now form the basis of estimation of risk for diabetes," he urged.

However, it is true that there is also great variability among diabetics as well, Dr. Colhoun noted, stressing that her study results refer to averages. Some people with type 1 diabetes "live to a ripe old age," while others die decades before they should, she noted.

One key factor in predicting mortality is glycemic control. "We clearly see a relationship between glycemic control and cardiovascular outcomes...and renal disease, which is also hugely associated with glycemic control." The biggest killer in type 1 diabetes is cardiovascular disease, which was responsible for 25% of deaths in the Scottish diabetes patients.

"The elephant is the room is this one-third of patients who are nowhere near the [ideal] level of glycemic control of HbA1c less than 7%," she noted.

One of the difficulties, however, is that it is "often difficult to get good sugar control without the risk of hypoglycemia," she said, stressing that "much greater emphasis needs to be put on psychological care" to encourage and enable self-care by people with type 1 diabetes. "There are quite a lot of data to show that this impacts positively, empowering people with type 1 diabetes."

Better glycemic control would also help reduce the 7.5% of deaths among type 1 diabetics due to "acute diabetic complications," which refer to acute hypoglycemia or acute hyperglycemia, she noted.

Another issue that could help in this regard is increasing the use of insulin-pump technology, she said. Although she acknowledged "this is not a solution for everyone," she said there are many people who could benefit from use of these devices who do not currently have access to them or are not using them.

And, of course, there is still much room for improving the management of other important risk factors in the type 1 diabetes population, she stressed.

And even with good risk-factor control, "some patients progress more quickly to eye and kidney disease, for example, than others," so much more research is needed to examine why this might be, she concluded.

European Association for the Study of Diabetes 2013 Meeting. Abstract 301, presented September 25, 2013.


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