Glycosylated hemoglobin: A screening test for diabetes mellitus?

Abstract

Glycosylated hemoglobin (GHb), or HbA, is now a popular test in the management of Insulin Dependent Diabetes (IDDM) as it provides an integrated measure of blood glucose concentrations over the preceding 1–3 months. In this report we evaluate its potential as an epidemiologic screening tool through its relationship to the standard diagnostic test—an Oral Glucose Tolerance Test (OGTT). Using data from over 400 relatives of IDDM patients, thought to be free of diabetes, we demonstrate that there was a significant correlation between GHb and glucose concentrations during an OGTT (maximum correlation, r = 0.27, P < 0.001). This was largely limited to adults. However, only 37% of the relatives who were found to have a diabetic OGTT also had a GHb above the normal range (mean ± 2 SD). Furthermore, only 25% of those with either diabetes or impaired glucose tolerance had an abnormal GHb. We thus conclude that GHb is too insensitive a measure to be used as a screening tool for the detection of diabetes mellitus as currently defined.