Growth hormone and somatomedin in insulin-dependent diabetes mellitus.

In order to study the interrelationship of GH, somatomedin (SM), and growth in insulin-dependent diabetes mellitus (IDDM), concentrations of serum glucose, serum GH, and plasma SM were determined at 2-h intervals for 48 h in 19 ambulatory children with IDDM of at least 2-yr duration (mean duration, 6 yr) and in 9 normal age-matched controls. Serum glucose was significantly elevated (P less than 0.001) in subjects with IDDM compared to controls [287 +/- 15 mg/dl vs. 99 +/- 2 mg/dl (mean +/- SEM)] as was the hemoglobin A1C (11.0 +/- 0.40% vs. 4.59 +/- 0.08%) and the serum GH (8.4 +/- 0.4 ng/ml vs. 5.6 +/- 0.6 ng/ml; P less than 0.002). Despite evidence of inadequate diabetes control and elevated GH levels, the subjects with IDDM had normal SM levels (1.82 +/- 0.14 U/ml) compared to their age-matched controls (mean, 1.66 +/- 0.19 U/ml) and normal growth. Furthermore, SM levels did not show any significant diurnal variation in either group. There was no significant correlation in either group between the mean plasma SM concentrations and the mean serum GH or mean serum glucose concentration of each subject. These findings of normal SM levels and elevated GH levels in these children with normal stature and IDDM suggest a partial block in GH action.