Insulin sensitivity and beta-cell function in adults with lifetime, untreated isolated growth hormone deficiency

: GH reduces insulin sensitivity (IS), whereas IGF-I increases it. IGF-I seems to be critical for the development of the -cells, and impaired IS has been reported in GH deficiency (GHD). Objective: The aim of the study was to assess IS and -cell function in adult patients with untreated isolated GHD (IGHD) due to a homozygous mutation in the GHRH receptor gene. Design, Setting, and Patients: We conducted a cross-sectional study in 24 GH-naive adult IGHD subjects and 25 controls. Intervention:We performed an oral glucose tolerance test with glucose and insulin measurements at 0, 30, 60, 90, 120, and 180 min. Main Outcome Measures: IS was assessed by homeostasis model assessment index of insulin resistance (IR), quantitative IS check index, oral glucose IS in 2 h (OGIS2) and 3 h (OGIS3). -Cell function was assayed by homeostasis model assessment index-, insulinogenic index, and area under the curve of insulin-glucose ratio. Results:During the oral glucose tolerance test, glucoselevelswere higherinIGHD subjects (P0.0001), whereas insulin response presented a trend toward reduction (P 0.08). The number of individuals with impaired glucose tolerance was higher in the IGHD group (P 0.001), whereas the frequency of diabetes was similar in the two groups. Homeostasismodel assessment index of IR was lower (P0.04), and quantitative IS check index and OGIS2 showed a nonsignificant trend toward elevation (P 0.066 and P 0.09, respectively) in IGHD. OGIS3 showed no difference between the groups. Homeostasis model assessment index-, insulinogenic index, and ratio of the areas of the insulin and glucose curves were reduced in the IGDH group (P 0.015, P 0.0001, and P 0.02, respectively). Conclusions: Adult subjects with lifetime congenital untreated IGHD present reduced -cell function, no evidence of IR, and higher frequency of impaired glucose tolerance. (