Metabolic Control in 131 Juvenile-onset Diabetic Patients as Measured by HbA_1c: Relation to Age, Duration, C-Peptide, Insulin Dose, and One or Two Insulin Injections

Glycosylated hemoglobin A (HbA_1c), considered to reflect long-term metabolic control of diabetes, was analyzed in 131 patients, aged 2 5/12–19 6/12 yr, with juvenile-onset diabetes. Using stepwise multiple regression HbA_1c, fasting blood glucose and plasma 3-hydroxybutyrate were analyzed as dependent variables versus independent variables such as age of the patients, duration of the disease, level of plasma immunoreactive C-peptide (IRCP), insulin dose, and number of insulin injections (one or two) per day. HbA_1c was inversely related only to IRCP concentration. A low but significant, positive correlation was found between HbA_1c and the duration of diabetes. Stepwise addition of the other independent variables did not further increase the fraction of explained variance. HbA_1c was also correlated with a subjective rating score of the metabolic control performed by the treating physician. Fasting plasma glucose was significantly related to HbA_1c but not to any of the independent variables. Fasting 3-hydroxybutyrate showed an inverse correlation to the age of the patient. The present study showed that in juvenile-onset diabetic patients, endogenous insulin secretion as reflected by IRCP was the factor best correlated with a low level of HbA_1c. After the cessation of endogenous insulin secretion, there is a progressive deterioration of metabolic control and multiple injections of insulin rather than one or two per day may be needed to reach optimal control in the patients.