Objective: To investigate the effect of growth hormone (GH) treatment on glucose metabolism in achondroplasia (ACH) patients.
Patients and methods: Twenty-five GH-treated (0.35 mg/kg/week) ACH patients (10 males and 15 females) were included in this study. Oral glucose tolerance test (OGTT) was performed at three time points; pre-treatment (age: 4.0±1.9 years), post short-term treatment (age: 6.5±3.0 years), and post long-term treatment (age: 11.8±3.4 years). We evaluated homeostasis model assessment of insulin resistance (HOMA-IR, fasting insulin (μU/mL) × fasting glucose (mg/dL) / 405) and β cell function by calculating insulinogenic index (IGI, Δinsulin (μU/mL) / Δglucose (mg/dL)). Statistical analysis was performed with Mann-Whitneys U test or analysis of variance (ANOVA) followed by multiple comparison using Tukeys test.
Results and discussion: No patients were diagnosed as diabetes mellitus throughout the observation period. Prediabetes was detected at least one time point in 32% (8/25) of the patients before or after initiation of GH administration (prediabetes group). GH treatment increased both HOMA-IR (pre: 0.7±0.4, post short-term: 1.9±1.2, post long-term: 2.2±0.9, P<0.01) and IGI (pre: 0.25±0.19, post short-term: 0.98±0.42, post long-term: 1.02±0.51, P<0.05), although the increase was within normal range. There was no difference in HOMA-IR between the prediabetes and the normal groups at pre-treatment or post long-term GH treatment. However, in the prediabetes group, HOMA-IR was higher at post short-term GH treatment (2.6±1.5 vs 1.6±0.8, P<0.05). IGI was lower at pre-treatment in the prediabetes group than in the normal group (0.06±008 vs 0.38±0.05, P<0.01), but there was no significant difference during GH treatment.
Discussion and conclusion: Although residual β cell function sufficiently counteracts insulin resistance induced by GH, OGTT may demonstrate prediabetes in ACH patients with low β cell function. Since low IGI at pre-treatment and/or marked increase of HOMA-IR at post short-term GH treatment seems to be related to transient prediabetes, vigilant monitoring of glucose metabolism should be performed when administrating GH to ACH patients with these findings.
Disclosure: The authors declared no competing interests.