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Introduction: Growth hormone (GH) is a central hormone for regulating linear growth during childhood and also highly involved in the metabolism of lipids, carbohydrates, and protein. However, few studies report on how treatment with GH during childhood influences metabolic parameters. Our aim was to investigate metabolic effects of different doses of GH in short children with GH peak levels in the low to normal range. Design: Thirty-five prepubertal short children (<-2.5 SDS), aged 7-10 years, with peak levels of GH between 7 and 14 mu g/L during an arginine-insulin tolerance test, were randomized to 3 different doses (11/33/100 mu g/kg/day) of GH treatment for 2 years. Auxological and metabolic investigations were performed. These included metabolites in blood and interstitial microdialysis fluid, dual-energy X-ray absorptiometry, frequently sampled intravenous glucose tolerance test (FSIVGTT), and stable isotope examinations of rates of glucose production and lipolysis. Results: At 24 months, the high-dose group (HD) had higher fasting insulin compared with the standard-dose (SD) and low-dose (LD) groups (HD: 111.7 vs. SD: 61.2 and LD: 46.0 pmol/L [p < 0.001]) and showed signs of insulin resistance (HOMA-IR, HD: 4.20 vs. SD: 2.17 and LD: 1.71 (LD) [p < 0.001]). The FSIVGTT also demonstrated higher acute insulin response (p < 0.05). Few other metabolic differences were found at 24 months, but a decreased insulin sensitivity index (Si) could already be seen at 12 months for both SD and HD compared with the LD group (p < 0.05). Conclusion: Treatment with GH resulted in a dose-dependent decrease in insulin sensitivity, demonstrated by higher levels of fasting insulin and signs of insulin resistance in both HOMA indices and FSIVGTT examinations.

Context: Type 1 diabetes is associated with portal insulin deficiency and disturbances in the GH-IGF axis including low circulating IGF-I and GH hypersecretion. Whether peripheral hyperinsulinemia and GH hypersecretion, which are relevant to the development of vascular complications, result in elevated tissue IGF-I remains unknown. Objective: The purpose of this study was to determine the relationship between whole-body glucose uptake and tissue IGF-I measured by microdialysis. Design: This was a single-blind placebo-controlled crossover study. Setting: The setting was a tertiary pediatric endocrine referral center. Participants: The participants were seven young male adults with type 1 diabetes. Intervention: After an overnight fast, a 6-h lasting euglycemic clamp was performed (constant insulin infusion at 0.5mU/kg x minute and variable glucose infusion rate [GIR]) and a subcutaneous injection of recombinant human (rh) IGF-I (120 mu g/kg) or saline was given after 2 hours. In parallel, tissue IGF-I levels were determined by microdialysis (md-IGF-I). Main Outcome Measures: md-IGF-I levels in muscle and subcutaneous fat, and GIR were determined. Results: md-IGF-I levels were detectable but unchanged after saline. After rhIGF-I, muscle and subcutaneous fat md-IGF-I increased during the second and third hour and then reached a plateau up to 10-fold higher than baseline (P less than .001). GIR was unchanged after saline, whereas it increased 2.5-fold concomitantly with the increase in md-IGF-I (P less than .0001). In contrast, serum IGF-I was increased already at 30 minutes after rhIGF-I and reached a plateau 2-fold above baseline (P less than .0001). Conclusion: We demonstrate that md-IGF-I measurements are valid and physiologically relevant by reflecting rhIGF-I-induced glucose uptake. Future studies should be conducted to elucidate the role of local tissue IGF-I in diabetic vascular complications., Funding Agencies|Jalmari and Rauha Ahokas Foundation; Samariten Foundation; Swedish Child Diabetes Foundation (Barndiabetesfonden); Foundation Frimurare Barnhuset in Stockholm; Society for Child Care (Sallskapet Barnavard); HRH Crown Princess Lovisa Society for Medicine; Stockholm County Council; ISPAD; Biomedicum Helsinki Foundation; Finnish Foundation for Pediatric Research; NovoNordisk (Bagsvaerd, Denmark); Ipsen (Kista, Sweden)

Background/Aims: Growth hormone insensitivity syndrome (GHIS) is caused by a defective growth hormone receptor (GHR) and is associated with insulin-like growth factor-I (IGF-I) deficiency, severely short stature and, from adolescence, fasting hyperglycemia and obesity. We studied the effects of treatment with IGF-I in either a 1:1 molar complex with IGFBP-3 (IGF-I/BP-3-Tx) or with IGF-I alone (IGF-I-Tx) on metabolism and linear growth. Methods: Two brothers, compound heterozygous for a GHR gene defect, were studied. After 8 months without treatment, we examined the short- and long-term effects of IGF-I/BP-3-Tx and, subsequently, IGF-I-Tx on 12-hour overnight levels of IGF-I, GH, insulin, IGFBP-1, insulin sensitivity by hyperinsulinemic euglycemic clamp, body composition by dual-energy X-ray absorptiometry and linear growth. Results: Mean overnight levels of insulin decreased and IGFBP-1, a measure of hepatic insulin sensitivity, increased on both regimens, but was more pronounced on IGF-I-Tx. Insulin sensitivity by clamp showed no consistent changes. Lean body mass increased and abdominal fat mass decreased in both subjects on IGF-I-Tx. However, the changes were inconsistent during IGF-I/BP-3-Tx. Height velocity was low without treatment, increased slightly on IGF-I/BP-3-Tx and doubled on IGF-I-Tx. Conclusion: Both modalities of IGF-I improved determinants of hepatic insulin sensitivity, body composition and linear growth rate; however, IGF-I alone seemed to be more efficient.

Congenital hyperinsulinism of infancy (CHI) is characterized by severe hypoglycemia due to dysregulated insulin secretion, associated with either focal or diffuse pathology of the endocrine pancreas. The focal condition is caused by a paternally inherited mutation in one of the genes encoding the subunits of the beta-cell ATP-sensitive potassium channel (SUR1/ABCC8 or Kir6.2/KCNJ11) and somatic loss of maternal 11p15 alleles within the affected area. Until now, preoperative diagnostics have relied on technically demanding and invasive catheterization techniques. We evaluated the utility of fluorine-18 L-3,4-dihydroxyphenylalanine ([F-18]-DOPA) positron emission tomography (PET) to identify focal pancreatic lesions in 14 CHI patients, 11 of which carried mutations in the ABCC8 gene (age 1-42 months). To reduce bias in PET image interpretation, quantitative means for evaluation of pancreatic [F-18]-DOPA uptake were established. Five patients had a visually apparent focal accumulation of [F-18]-DOPA and standardized uptake value (SUV) >50% higher (mean 1.8-fold) than the maximum SUV of the unaffected part of the pancreas. When these patients were operated on, a focus of 4-5 X 5-8 nun matching with the PET scan was found, and all were normoglycentic after resection of the focus. The remaining nine patients had diffuse accumulation of [F-18]DOPA in the pancreas (SUV ratio < 1.5). Diffuse histology was verified in four of these, and pancreatic catheterization was consistent with diffuse pathology in four cases. In conclusion, [F-18]-DOPA PET is a promising noninvasive method for the identification and localization of the focal form of CHI.