Evalutation of Insulin Sensitivity Through Hyperinsulinemic Clamp in Children With GH Deficiency

Comparison Between Euglycemic Hyperinsulinemic Clamp and Surrogate Indexes of Insulin Sensitivity in Children With Growth Hormone Deficiency.

Data about the impact of growth hormone treatment on insulin sensitivity in children are quite controversial, due to the different surrogate indexes that have been used, like Homa-IR, QUICKI, ISI-Matsuda or adipokine levels.

The investigators aimed to evaluate insulin sensitivity through the euglycemic hyperinsulinemic clamp, considered the gold standard technique, in children affected by growth hormone deficiency and to compare the M-value with the most commonly used surrogate indexes of insulin sensitivity.

The investigators aimed of this study was to use the hyperinsulinemic clamp to evaluate the impact of GH treatment on insulin-stimulated glucose utilization (M-value) in a group of children affected by GH deficiency and to compare the clamp-derived index with the most commonly used surrogate indexes of insulin sensitivity.

In all patients the auxological and metabolic evaluation was performed at baseline and after 12 months of GH treatment, while in controls these evaluations were only performed at baseline. In all children the investigators measured body height, body mass index (BMI) and waist circumference (WC). A blood sample was drawn after an overnight fast for the measurement of glucose, insulin, Hemoglobin A1c (HbA1c) and IGF-I. This sample served as the baseline for the oral glucose tolerance test (OGTT). Blood samples were collected every 30 min for 120 min for glucose and insulin measurements. As surrogate estimates of insulin sensitivity the investigators used the insulin sensitivity index, a composite index derived from the OGTT and validated by Matsuda and DeFronzo (ISI-Matsuda). On a different day, as a gold standard measurement of insulin sensitivity the investigators performed the euglycemic hyperinsulinemic clamp. As other insulin sensitivity markers, the serum levels of adiponectin and resistin after an overnight fast were also measured.

Inclusion Criteria:

• Isolated idiopathic GH deficiency diagnosed by the auxological and biochemical criteria of the GH Research Society in prepubertal children
• Prepubertal children

Exclusion Criteria:

• Children with multiple hormone deficiency
• Children receiving other hormonal replacement treatment
• Pubertal children