Metabolic control in 131 juvenile-onset diabetic patients as measured by HbA1c: relation to age, duration, C-peptide, insulin dose, and one or two insulin injections.

Glycosylated hemoglobin A (HbA1c), 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 HbA1c, 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. HbA1c was inversely related only to IRCP concentration. A low but significant, positive correlation was found between HbA1c and the duration of diabetes. Stepwise addition of the other independent variables did not further increase the fraction of explained variance. HbA1c was also correlated with a subjective rating score of the metabolic control performed by the treating physician. Fasting plasma glucose was significantly related to HbA1c 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 HbA1c. 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.