The Brits strike again, undermining what we all think we know! The article summarized here calls into question the practice of using A1c or fasting glucose to diagnose “pre-diabetes” (a “disease” which I put in “quotations” because it’s a “pre-disease.”)
Screening for pre-diabetes: neither HbA1c nor fasting glucose results are very accurate
Are screening tests for pre-diabetes accurate?
“What’s in a name?” Juliet pondered… to her detriment, as it turned out. So, too, with the diagnosis of “pre-diabetes.” In this analysis, an elevated (by various criteria) HbA1c or fasting plasma glucose level only sometimes lines up with impaired glucose tolerance testing results via a glucose tolerance test. If we take an abnormal 2-hour glucose tolerance test result to be the true harbinger of eventual type 2 diabetes, an HbA1c level is neither sensitive or specific and a fasting glucose is specific (can accurately rule-in risk) but not sensitive. Depending on the screening test you use (or are required to use), many people will receive an incorrect diagnosis, while others will be falsely reassured. (LOE = 1a-)
Barry E, Roberts S, Oke J, Vijayaraghavan S, Normansell R, Greenhalgh T. 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;356:i6538.