Glycosylated haemoglobin levels in patients referred for oral glucose tolerance tests.

Oral glucose tolerance tests (OGTTs) were performed on 127 patients, and the results interpreted according to the WHO criteria. Glycosylated haemoglobin (GHb), assayed by affinity chromatography, was measured on the fasting blood specimen. All patients classified as diabetic were found to have GHb results greater than 9.9%. There was no overlap with the normal group, all of whom had GHb results less than 8.8%. In the diabetic patients, GHb showed good correlations with both fasting and 2-hour post-glucose blood glucoses. By contrast the non-diabetic group showed only poor correlations between GHb and the fasting and the 2-hour blood glucose concentrations. Overall, the best correlation was found between GHb and the mean of the five blood glucose results obtained during the OGTT.