Screening for pre-diabetes and effectiveness of interventions
Compiled by Vari Drennan, professor of healthcare and policy research, Kingston University, London and St George’s University of London
Pre-diabetes screening and diagnostic criteria varies internationally. This systematic review assessed the diagnostic accuracy of screening tests for pre-diabetes and efficacy of interventions (lifestyle changes or metformin) in preventing onset of type 2 diabetes in people with pre-diabetes.
The first meta-analysis of 49 studies examined the evidence for two screening tests: fasting glucose and HbA1c. The fasting glucose test was found to be specific as it identified true negatives, but not sensitive because it did not identify all true positives.
The HbA1c test was found to be neither sensitive nor specific as it gave false positive and false negative results. If these are used as screening tests then significant numbers of people will receive an inaccurate diagnosis while many others will be falsely reassured.
The second meta-analysis of 50 studies found using metformin gave a relative risk reduction of 26% while participants were taking this drug. Interventions to change lifestyles were associated with a 36% reduction in relative risk of type 2 diabetes but dropped to 20% at follow up. Social support and economic resources had an impact on attrition rates.
The authors conclude that screen and treat policies alone are unlikely to impact on the increasing prevalence of diabetes.
Barry E, Roberts S, Oke J et al (2017) Efficacy and effectiveness of screen and treat policies in prevention of type 2 diabetes: systematic review and meta-analysis of screening tests and interventions. BMJ. 2017 Jan 4; 356:i6538. doi: 10.1136/bmj.i6538