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

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 b-cell function (bCF) 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 bCF 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 bCF. The purposes of thiswork were to verify the prevalence of IGTandDM in adultMUT/MUTsubjects fromthis kindred and to compare IS and bCF inMUT/MUTandMUT/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 homeostaticmodel assessment of insulin resistance (HOMA-IR), quantitative IS check index, and oral glucose IS index for 2 and 3 h. bCF was assayed by HOMA-b, 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 bCF was reduced in MUT/MUT in comparison with MUT/N. Conclusions: Lifetime, untreated IGHD increases IS, impairs bCF, and does not provide protection from diabetes