Type 1 diabetes cuts lifespan by more than a decade

Until the early years of the last century, most children with diabetes slipped into fatal comas within a few months of developing the disease.¹ Insulin's introduction in 1922 and improvements in care over the last 20 to 30 years – including home blood glucose testing, earlier detection and improved management of complications – transformed the prognosis for type 1 diabetes (T1D).
A new paper reported that life expectancy at 20 years of age for T1D patients in Scotland is still more than a decade shorter than the general population's.² Meanwhile, Diabetes UK's recent State of the Nation report noted that 'some people with diabetes' including those with T1D receive 'considerably worse routine care than other people with diabetes' leaving them at risk of serious complications, disability and premature death.³
Previous estimates of the loss of life expectancy in people with T1D ranged from 20 to 27 years. The new study sampled 24,691 people and so provides 'estimates that reflect actual contemporary death rates'. During the study, which ran from 2008 to 2010, 1043 people died.²
For 20 year olds with T1D, life expectancy was a further 46.2 years, compared to 57.3 years for men without diabetes. So, T1D reduced life expectancy by 11.1 years. Life expectancy at age 20 years was another 48.1 years among women with T1D and 61 years among women without diabetes, a loss of 12.9 years. In the general population, 76% of men and 83% of women lived to 70 years of age. This compared with 47% and 55% respectively of those with T1D.²
Some studies have suggested that mortality might not be elevated in T1D patients without renal disease. So, the researchers looked at people with T1D who had estimated glomerular filtration rates (eGFR) of 90ml/min/1.73m2 or higher. Despite their preserved renal function, the estimated loss in life expectancy from age 20 years was 8.3 years for men and 7.9 years for women. As expected, the risk of mortality rose as renal function declined: 1.74 for stage 3 chronic kidney disease, 4.70 for stage 4, and 8.70 for stage 5 compared with patients with an eGFR of more than 90 ml/min/1.73m2.2
Renal failure was the underlying cause of death for 5.7% of men and 6.2% of women with T1D. In addition, renal disease contributes to cardiovascular disease, which accounted for 45% of deaths in men and 42% of women. However, diabetic coma or ketoacidosis was associated with the largest proportion of the estimated loss before 50 years of age: 29.4% in men and 21.7% in women. Avoiding deaths from diabetic coma or ketoacidosis would reduce the loss of life expectancy in men to 9.3 years.²
Against this background, the State of the Nation report suggested only 57% and 81.2% of people with T1D in England had had their urine albumin and serum creatinine measured, respectively. About 80% had had their HbA1c (80.9%), blood pressure (89.0%) and cholesterol (78.2%) measured. Levels of these and the other critical care processes in T1D – foot surveillance (72.7%), measuring BMI (84.4%) and recording smoking status (80%) – were lower than for those with T2D. Overall, just 41.4% of T1D patients received all eight care processes compared with 61.5% of those with T2D. Younger people were less likely to receive these care processes.
However, only 16% of people with T1D and 37% with T2D met all three treatment targets – for blood pressure (attained by 73.4%), cholesterol (70.2%) and HbA1C (27.6%). Again, younger people were less likely to attain treatment targets. In addition, the proportion of patients who meet all three targets varied by 20 to 30 percentage points between CCGs. In some CCGs, less than 10% of people with T1D met all three treatment targets.³
The Scottish paediatric dataset contained 15 deaths in 11,143 person-years in people younger than 20 years. The estimated loss in life expectancy from birth with T1D was 11.7 years in males and 13.6 years in females.² In 2012-13, only 12.1% of people between 12 to 24 years of age in England received all seven recommended care processes, although this is roughly double (6.7%) the rate in 2011-12. Smoking isn't included in the young person's process.³
A lack of data meant the authors could not assess whether the Scottish findings applied to other countries. However, levels of risk factors and HbA1c, and risk factor control among T1D patients in Scotland were similar to those in England. The Scottish rates were somewhat higher than in some European countries and some cohorts from the USA, which could lead to a greater loss of life expectancy in Scotland.2 As the State of the Nation report concluded 'there is clearly a long way to go before everyone with diabetes receives high quality care'.³