Effect of glycemic control on growth velocity in children with IDDM.

OBJECTIVE: To determine the effect of glycemic control on growth velocity in children with insulin-dependent diabetes mellitus. RESEARCH DESIGN AND METHODS: One hundred twenty-two children with insulin-dependent diabetes mellitus were studied over a 5-yr period. Every 4 mo, glycemic control was assessed by measuring total glycosylated hemoglobin (GHb), pubertal status was determined by physical examination, and height was measured with a stadiometer. Height measurements were normalized for age and sex by converting them to tau scores (the number of SD above or below the mean for age and sex). Alterations in growth velocity were determined by the change in tau scores (delta tau) between visits (i.e., no change in tau score = normal growth velocity; decrease in tau score = growth deceleration; and increase in tau score = growth acceleration).
RESULTS: A linear relationship was seen between GHb levels and the change in tau scores (r = -0.117, P = 0.001). GHb values less than 8% were associated with growth acceleration (delta tau = +0.10 +/- 0.03), and the greatest growth deceleration occurred when GHb was greater than 16% (delta tau = -0.07 +/- 0.03). The level of GHb at which growth suppression occurred (mean delta tau became negative) was dependent on pubertal status: Tanner stage 1 greater than or equal to 10%, Tanner stages 2 and 3 greater than or equal to 8%, Tanner stages 4 and 5 greater than or equal to 16%.
CONCLUSIONS: Linear growth velocity in children with insulin-dependent diabetes mellitus is heavily related to metabolic control. Children who are prepubertal or in the early stages of puberty are the most vulnerable to growth suppression. Once puberty is well established, growth suppression does not occur until marked hyperglycemia (GHb greater than 16%) exists.