Lifetime congenital isolated GH deficiency does not protect from the development of diabetes

Abstract

OBJECTIVES: Adult subjects with untreated, lifetime, isolated GH deficiency (IGHD) due to a homozygous GHRH receptor gene mutation (MUT/MUT) residing in Itabaianinha, Brazil, present with lower BMI, higher prevalence of impaired glucose tolerance (IGT), increased insulin sensitivity (IS), and reduced beta-cell function (betaCF) when compared with non-BMI-matched homozygous normal controls. However, the prevalence of diabetes mellitus (DM) in this cohort is unknown. Comparing their IS and betaCF with BMI-matched individuals heterozygous for the same mutation (MUT/N) may be useful to elucidate the role of the GH-IGF1 axis in IS and betaCF. The purposes of this work were to verify the prevalence of IGT and DM in adult MUT/MUT subjects from this kindred and to compare IS and betaCF in MUT/MUT and MUT/N. DESIGN: Cross-sectional study. METHODS: We studied most (51) of the living IGHD adults of this kindred who are GH naive. The oral glucose tolerance test (OGTT) could be performed in 34 subjects, fasting glucose was measured in 15, while two had a previous diagnosis of DM. The OGTT results of 24 MUT/MUT subjects were compared with those of 25 BMI-matched MUT/N subjects. IS was assessed by homeostatic model assessment of insulin resistance (HOMA-IR), quantitative IS check index, and oral glucose IS index for 2 and 3 h. betaCF was assayed by HOMA-beta, insulinogenic index, and the area under the curve of insulin:glucose ratio. RESULTS: The prevalence of DM and IGT in IGHD was 15.68 and 38.23% respectively. IS was increased and betaCF was reduced in MUT/MUT in comparison with MUT/N. CONCLUSIONS: Lifetime, untreated IGHD increases IS, impairs betaCF, and does not provide protection from diabetes.