Monitoring Metabolic Control in Diabetic Outpatients with Glycosylated Hemoglobin

Abstract

The usefulness of HbA₁ as a monitor of metabolic control was studied in 15 diabetic outpatients during periods of stable, deteriorating, and improving control. Mean fasting concentrations of HbA₁ and plasma glucose during a 3-month period of stable control were 12.6% ± 0.8% and 120 ± 8 mg/dL, respectively. One week after discontinuation of oral hypoglycemic therapy, blood glucose had risen to 172 ± 23 mg/dL and HbA₁ to 14.1% ± 0.7% (P < 0.025). Reinstitution of therapy resulted in a significant fall of blood glucose within 2 weeks. A significant decline in HbA₁ (from 15.3% ± 0.8% to 14.1% ± 0.9%, P < 0.025) occurred 2 weeks later. The data show that the rate of formation of HbA₁ is considerably faster than its rate of disappearance. Thus, HbA₁ is likely to reflect disproportionally recent episodes of poor control. We conclude that HbA₁ is useful to monitor diabetic outpatients during periods of stable and rapidly deteriorating control but is not suited to detect rapid metabolic improvements.