Type 2 diabetes screening failed to reduce mortality in UK

Benefits to screening for type 2 diabetes may not be as high as previously thought, according to researchers from the United Kingdom, who found no significant reduction in cardiovascular-, cancer- or diabetes-related mortality associated with population-based screening.

Researchers in eastern England conducted a pragmatic parallel-group, cluster-randomized trial that included 33 general practices known as the ADDITION-Cambridge study. Each practice was randomly assigned to one of three groups: screening with intensive multifactorial treatment for those diagnosed with diabetes (n=15); screening plus routine care of diabetes based on national guidelines (n=13); and a control group with no screening (n=5).

More than 15,000 patients at high risk for prevalent undiagnosed diabetes (n=15,089) were invited to participate in stepwise screening programs between 2001 and 2006. Screening included random capillary blood glucose and HbA1c tests, a fasting capillary blood glucose test and a confirmatory oral glucose tolerance test, according to the study abstract. The mean age of the patients was 58 years, and mortality surveillance was conducted through the England and Wales Office for National Statistics.

Nearly three-quarters of patients (73%) attended screening, 3% of whom received a diagnosis of diabetes. Controls (n=4,137) were followed.

After nearly 10 years of follow-up (median: 9.6 years), 1,532 screening patients and 377 controls died.

Cancer was the most common cause of death, and all-cause mortality was not significantly different between the screening and control groups (HR=1.06; 95% CI, 0.90-1.25). Additionally, there was no significant difference between groups regarding CV mortality, cancer mortality or other causes of death, according to the researchers.

“Diabetes was listed among other causes of death in 91 individuals (75 in the screening group and 16 in the control group),” they wrote. “There was no significant difference between groups in diabetes-related mortality (HR=1.26; 95% CI, 0.75-2.10).”

Results of the parallel-group cohort analysis demonstrated 2,769 deaths in 49 screening practices between November 2001 and November 2011. Additionally, there was no significant difference in all-cause mortality (HR=0.98; 95% CI, 0.84-1.14), CV mortality (HR=0.92; 95% CI, 0.70-1.22), cancer mortality (HR=1.00; 95% CI, 0.80-1.20), diabetes-related mortality (HR=0.97; 95% CI, 0.58-1.61) or other causes of death (HR=1.00; 95% CI, 0.80-1.25) among those screened vs. non-screened controls.

“Invitation to a single round of screening for type 2 diabetes in high-risk individuals in UK general practice might benefit the minority with detectable disease but was not associated with a reduction in all-cause or diabetes-related mortality over 10 years,” the researchers concluded. “If population-based screening for diabetes is to be implemented, it should be undertaken alongside assessment and management of risk factors for diabetes and cardiovascular disease and population level preventive strategies targeting underlying determinants of these diseases.”

In an accompanying editorial, Michael M. Engelgau, MD, MS, and Edward W. Gregg, PhD, both of the CDC, said the study increases the doubt surrounding the value of widespread screening for diabetes alone. However, mortality will not be the sole outcome upon which the judgment to screen will depend.

“Screening and early actions could have an important benefit in terms of chronic disease risk factor improvement, incidence of disease, morbidity, quality of life, and costs, without materially affecting mortality,” Engelgau and Gregg wrote. “If we are to rely on cost-effectiveness modeling as a means to guide screening policy, we will have to place a lot of faith in the assumptions and effect of early identification on quality of life.”

For more information:

Engelgau MM. Lancet. 2012;doi:10.1016/S0140-6736(12)61682-1.

Simmons RK. Lancet. 2012;doi:10.1016/S0140-6736(12)61422-6.

Disclosure: Some of the study researchers report previous financial ties with Eli Lilly and Novo Nordisk.