Larry Hand

October 04, 2012

October 4, 2012 — Screening and intervention for type 2 diabetes in a British population had no effect on all-cause mortality during a 10-year period, according to a study published online October 4 in The Lancet and presented that same day during the annual meeting of the European Association for the Study of Diabetes (EASD) in Berlin, Germany.

Rebecca K. Simmons, PhD, from the Medical Research Council (MRC) Epidemiology Unit in Cambridge, United Kingdom (UK), and colleagues conducted a randomized trial involving 33 general medical practices in eastern England. They first randomly assigned the practices to 1 of 3 groups: a control group that received no screening (n = 5 practices), screening followed by intensive diabetes care (n = 15), and screening followed by routine care (n = 13). One screening practice dropped out before screening began, which left the number of intensive care practices at 14.

The screening practices accounted for 16,047 patients and the nonscreening practices accounted for 4137 patients; the median patient age was 58 years (range, 40 - 69 years). Of the 20,184 total individuals in 32 practices, 15,089 (94%) were invited, on the basis of predefined criteria, to screening between January 2002 and March 2006; 11,737 (73%) of them participated in the screening; and diabetes was diagnosed in 466 (3% of those eligible).

During a median follow-up period of 9.6 years, 1532 patients died in the screening group (mortality hazard ratio [HR], 1.06; 95% confidence interval [CI], 0.90 - 1.25; rate per 1000 person-years, 10.5; 95% CI, 9.99 - 11.04) and 377 died in the control group (rate per 1000 person-years 9.89; 95% CI, 8.94 - 10.94). Cancer was the most common cause of death in both groups.

"We noted no significant difference between groups in cardiovascular mortality, cancer mortality, or other causes of death," the researchers write. Of the other causes of death listed, diabetes was cited in 75 of the screening cases and 16 in the control group.

"In this large, population-based UK sample, all-cause mortality over a median 9.6 years was not reduced by one round of screening for type 2 diabetes in people at high risk of prevalent undiagnosed diabetes," they write.

The study population came from 1 of 2 phases of the ADDITION-Cambridge study of diabetes type 2 screening and intervention in British primary care clinics.

Limitations of the study include a possible lack of generalizability because the study was conducted in an area with above-average affluence, where disease risk may be lower than in other socioeconomic areas.

On the basis of this first-ever analysis of the effect of a population-based diabetes screening program, senior author Simon J. Griffin, DM, from the MRC's Addenbrooke Hospital unit in Cambridge, UK, said in a statement, "It seems that the benefits of screening might be smaller than expected and restricted to individuals with detectable disease.  However, benefits to the population could be increased by including the detection and management of cardiovascular risk factors alongside the assessment of diabetes risk, performing repeated rounds of screening, and improving strategies to maximize the uptake of screening."

In an accompanying commentary, Michael M Engelgau, MD, and Edward W. Gregg, PhD, from the Centers for Disease Control and Prevention in Atlanta, Georgia, write that the researchers "increase the doubt about the value of wide-scale screening for undiagnosed diabetes alone, and deserve credit for tackling the screening quandary head-on. Nevertheless, for any one study to address the diverse factors that affect screening policies — ranging from the magnitude of population burden of disease to the capacity and effectiveness of prevention approaches — is a tall order. Screening recommendations are therefore likely to be country-specific and context-specific for the foreseeable future."

Countries with higher prevalences of undiagnosed diabetes and lower quality of care might see a higher magnitude of benefits from diabetes screening, the commentary authors write.

Asked to comment on the study, EASD session moderator Rury Holman, FMedSci, FRCP, director of the Diabetes Trials Unit and professor of diabetic medicine at Oxford University, United Kingdom, told Medscape Medical News, "The question they were asking in this study was if you take the trouble and expense to find people and declare they are at risk of diabetes and test, and then the community — the healthcare system — presumably treats them, you think they would do better. But in the time scale of this study, that wasn't the case. It doesn't mean that you couldn't find them and put them in a special program, but if you put them into the normal health care system with an earlier label of diabetes than they would otherwise have, it doesn't bring any clinical advantages. [The study] says that the incremental benefit of finding people a few years earlier is quite small."

This study was supported by the Wellcome Trust; UK Medical Research Council: National Health Service; UK National Institute for Health Research; University of Aarhus, Denmark; and Bio-Rad. One author received an honorarium and travel expense reimbursement from Eli Lilly and payment from Novo Nordisk for a lecture; another has received payment from Novo Nordisk for a lecture. None of the other authors, the editorialists, or Dr. Holman have disclosed any relevant financial relationships.

Lancet. Published online October 4, 2012. Abstract