GROWTH-PARAMETERS, GROWTH-HORMONE (GH) RESPONSE TO CLONIDINE AND CIRCULATING INSULIN-LIKE GROWTH-FACTOR-I (IGF-I), FREE-THYROXINE (FT4) ANDCORTISOL CONCENTRATIONS IN RELATION TO GLYCEMIC CONTROL IN CHILDREN WITH INSULIN-DEPENDENT DIABETES-MELLITUS

The objective of this paper was to determine the effect of glycaemic c ontrol and endocrine functions on linear growth in children with IDDM. We studied 45 prepubertal children with IDDM (30 males, 15 females) o ver 1 year period. The mean+/-SD for age of onset and duration of IDDM were 6.2+/-2.3 years and 3.5+/-1.3 years, respectively. At each clini c visit (every 3 months), glycaemic control was assessed by measuring glycosylated haemoglobin (HbAlC). Growth hormone and cortisol response s to high dose clonidine (0.15 mg/m(2)) and ACTH, respectively, were e valuated and circulating concentrations of free thyroxine (FT4) and TS H estimated. The average insulin dose (unit/kg/day) during this period was calculated for each patient. Growth was assessed by determining b oth height standard deviation score (HtSDS) and growth velocity standa rd deviation scores (GVSDS) and bone age determined according to the a tlas of Greulich and Pyle. Two-hundred-and-lift age- and sex-matched n ormal children served as controls for growth data, and 20 normal age-m atched children and 20 normal children with short stature (NVSS) serve d as controls for the hormonal studies. Growth velocity (GV) (cm/year) and GVSDS were significantly lower in children with IDDM compared to normal children, and significantly lower in children with poorly contr olled diabetes compared to those with good glycaemic control. GV and G VSDS were inversely correlated to HbAlC (r = -0.356, P < 0.01 and r = 0.335, P < 0.01 respectively). GVSDS was correlated with serum IGF-I ( r = 0.22, P < 0.01), FT4 (r = 0.321, P < 0.01) and inversely with basa l CB (r = -0.362, P < 0.01) concentrations, but was not correlated wit h cortisol levels or peak GH concentrations in response to clonidine. GVSDS was correlated with HtSDS (r = 0.222, P < 0.01) and inversely wi th age (r = -0.43, P < 0.05). There was no significant correlation bet ween GVSDS on the one hand and weight gain or body mass index (BMI) on the other hand. Peak GH response to clonidine was correlated with BMI (r = 0.68, P < 0.001) and insulin dose/kg/day (r = 0.602, P < 0.01). This study confirms that in children with IDDM linear growth velocity is dependent on the age of the child and the degree of glycaemic contr ol, as well as on growth promoting hormones such as IGF-I and FT4. Hig h BMI is associated with more GH secretion in response to clonidine, t his might explain the higher requirements of insulin/kg in children wi th IDDM and high BMI.