Diagnosing type 2 diabetes on the basis of a single HbA1c test will miss nearly three-quarters of people with the disease, according to results announced at a major conference.

Presenting to delegates at the US Endocrine Society’s annual meeting in New Orleans, Dr Maria Chang Villacreses said that compared to an oral glucose tolerance test (OGTT), 73% of people with diabetes would be missed if diagnoses were made on the basis of an HbA1c test alone.

In the study of 9000 participants in the 2005-14 National Health and Nutrition Examination Survey aged over 20 years without a prior diagnosis of diabetes, Dr Chang Villacreses compared their results from an OGTT with those of an HbA1c test.

Using those classified as having diabetes by OGTT (fasting blood glucose >7mmol/L, two-hour post-challenge plasma glucose >11.1mmol/L) as a reference, the sensitivity of HbA1c for detecting diabetes was just 27%.