Insulin doses in children using conventional therapy for insulin dependent diabetes

The objective of this project was to develop plots of daily insulin dosages by percentile in diabetic children and to analyze various factors, such as metabolic control, age, and duration of diabetes that might influence the insulin prescription. Patients in extremely poor metabolic control (HbA1C > 9.8%) and patients with less than 1 year of diabetes were excluded from analysis. Patients were aged 2-21 years and the mean age at diagnosis was 8 years. Thirty-two percent of the patients were younger than 5 years and 15% were older than 15 years at diagnosis. Ninety-nine percent of patients used both regular and intermediate-acting (NPH or Lente) insulin 10-30 min before breakfast and again in the evening. Ten percent of the patients used only regular insulin at supper but used intermediate-acting insulin at bedtime. Insulin doses varied between 0.3 and 1.2 U/kg/day in prepubertal children (mean, 0.8 U/kg/day) and 0.5 and 1.8 U/kg body weight/day in pubertal children (mean, 1.25 U/kg/day). Average insulin doses in boys and girls were similar, except at ages 10-13, when the dose was significantly higher in girls. The insulin dose declined after age 17 in both genders to a value at age 21 that was 20-30% lower than the highest dose during pubertal years. Insulin dose did not correlate with duration of disease after 2 years, the ratio of morning to evening insulin, the ratio of regular to intermediate-acting insulin, or body mass. There was a slight association between higher insulin doses and higher glycosylated hemoglobin values. The results indicate that insulin requirements vary over a wide range in a group of children with metabolic control ranging from 'excellent' to 'fair' and correlate primarily with age and pubertal development. About 25% of prepubertal children and 50% of pubertal and post-pubertal children use more than 1 U insulin/kg/day--a dose commonly believed to be an 'upper limit' by many health professionals. The data should provide guidelines for the range of insulin dosing required to achieve fairly good to excellent control in diabetic children of various ages.