Glycosylated hemoglobin in patients with newly discovered juvenile-onset diabetes mellitus in the days immediately following the beginning of insulin treatment.

We studied the behavior of fast hemoglobin fractions in newly discovered diabetic patients, before and in the 10 days immediately following the beginning of insulin therapy, in order to verify whether or not the rapid improvement of glycemic control involved a rapid reduction of total HbA1 and of its fractions. We observed a rapid and highly significant fall of HbA1(a+b+c) and HbA1c levels after only 1 or 2 days of insulin therapy, followed by a slower decrement in the other 3-10 days. HbA1(a+b) showed a slower decrement trend, reaching levels significantly below baseline values only after 7-10 days. These results suggest that rapid changes occurring in glycosylated hemoglobin levels after the beginning of insulin treatment in newly discovered diabetic patients involve mainly HbA1c. The kinetics of glycosylated hemoglobin reduction, with a first rapid decrement followed by a slower one, may suggest the hypothesis that rapid changes are due to reversible Schiff base de-glycosylation, the ketoamine linkage being the true index of long term glycemic control.