Glycohemoglobin. Its use in the follow-up of diabetes and diagnosis of glucose intolerance.

In 140 persons with a normal glucose tolerance test (GTT), the median glycohemoglobin (GHb) level was 8.1% (95% limits, 6.5% to 9.0%). The GHb level was not significantly different in 30 patients with impaired GTT (8.6%). In all 14 patients with diabetic GTT and fasting plasma glucose (PG) level above 140 mg/dL, GHb level was above 10% (median, 11.3%). Of 25 patients with diabetic GTT but without fasting hyperglycemia, only two had GHb levels 10% or above. The GHb level correlated with the mean daily PG level in both 176 insulin-dependent (rs, +.530) and 107 non-insulin-dependent (rs, +.734) diabetics. Correlation was almost zero between GHb level and mean one-day PG level in 14 most brittle insulin-dependent diabetics. However, in them, there was a strong correlation (rs, +.763) between GHb level and the mean of 20 or more PG values for the preceding month. Follow-up of 100 diabetics showed strong correlation (rs, +.845) between the changes in GHb level and in the mea PG level. Decrease of the mean PG level of 100 mg/dL was accompanied by a drop of the GHb level of about 2%.