Age at Type 2 Diabetes Diagnosis Influences Mortality Risk

Pam Harrison

March 06, 2018

Being younger when diagnosed with type 2 diabetes is associated with an increased risk of all-cause and cardiovascular disease (CVD) mortality compared with being diagnosed at a later stage in life, a large Australian cohort study has shown.

"Evidence is accumulating to suggest that earlier onset of type 2 diabetes is associated with an increased risk of complications and comorbidities compared with later onset, and that the development and progression of complications might be more aggressive in those with earlier onset," say the authors, led by Lili Huo, MD, of the Baker Heart and Diabetes Institute in Melbourne, Australia.

"Early and aggressive risk factor management is warranted for individuals with young-onset type 2 diabetes," they conclude.

The research was published online February 22 in Diabetologia by Huo and colleagues.

Greater Risk of Noncancer Death With Younger Age at Diagnosis

Type 2 diabetes was considered a disease largely confined to older people, but the global epidemic of obesity and overweight in almost all countries has seen diagnoses rocket in young adults, adolescents, and even younger children.

Diabetes rates are increasing substantially in younger adults aged 20 to 45 years, which means there is a steadily growing pool of patients with type 2 diabetes exposed to the disease for a longer period in their lives.

The researchers analyzed data on 743 709 Australians diagnosed with type 2 diabetes between 1997 and 2011 from the National Diabetes Services Scheme.

The sample represented approximately 90% of all Australians diagnosed with type 2 diabetes over the study interval. Mortality was determined using data from the National Death Index.

The median age at diagnosis was 59 years and 115 363 deaths occurred over the 15-year study interval. The median follow-up was 7.2 years.

"At any given age, all-cause mortality rates were higher for a lower age of diagnosis (therefore longer duration) in both men and women," Huo and colleagues report.

For example, for two, 50-year-old men, one of whom was diagnosed with diabetes at the age of 45 years and the other at the age of 50 years, mortality from CVD was about 1.4 times higher in the one diagnosed 5 years earlier.

And the gap between mortality risk and death from any cause, as well as from CVD, was even greater when the difference in diabetes diagnosis was even longer. 

So the risk of death from any cause was about 30% greater for a 50-year-old man whose type 2 diabetes was diagnosed 10 years earlier while the risk of death from CVD was about 60% greater, compared with a 50-year-old man whose disease was diagnosed at age 50 years.

"Similar patterns were seen in women, though the excess risks of earlier-onset diabetes were slightly higher among women than among men," the researchers observe.

But Lower Cancer Mortality Associated With Younger Age at Diagnosis

In contrast, at any given age, "the earlier age at diagnosis was associated with lower cancer mortality and was most pronounced among women," the researchers observe.

They note that mortality rates from cancer were high just after being diagnosed with diabetes but then declined during the first 3 years following the diagnosis.

This may reflect the fact that patients with newly diagnosed diabetes are more likely to be in contact with healthcare professionals, making it more likely that undiagnosed cancer would be detected, the authors speculate.

They also hypothesize that the excess mortality risk in patients with younger-onset diabetes likely reflects increased exposure to hyperglycemia with longer disease duration.

"Our findings suggest that younger-onset type 2 diabetes increases mortality risk, and that this is mainly through earlier CVD mortality," investigators conclude.

"Efforts to delay the onset of type 2 diabetes might, therefore, reduce mortality," they conclude.

The study was funded by the National Health and Medical Research Council and the Victoria government's Operational Infrastructure Support program.

Diabetologia. Published online February 22, 2018. Abstract

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