Adiponectin, Leptin, and Erythrocyte Sodium/Lithium Countertransport Activity, But Not Resistin, Are Related to Glucose Metabolism in Growth Hormone-Deficient Adults

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In a randomized, placebo-controlled, crossover study under metabolic ward conditions, 10 GH-deficient adults received 1-wk GH replacement therapy (9.5 microg/kg.d). The effect of this treatment on the erythrocyte sodium/lithium countertransport (SLC) activity and on serum levels of adiponectin, resistin, leptin, IGF binding protein-1 (IGFBP-1) and IL-6 was determined. The 1-wk GH replacement impaired glucose homeostasis determined from an oral glucose tolerance test. The other measured variables in serum were unchanged by GH replacement. At baseline, serum adiponectin level was inversely correlated and serum leptin level was positively correlated with measures of glucose tolerance and insulin sensitivity. The changes in serum leptin level and erythrocyte SLC activity were positively correlated, and the change in serum IGFBP-1 level was negatively correlated, correlated with changes in measures of glucose metabolism. In conclusion, short-term GH treatment induced glucose intolerance but did not significantly change the erythrocyte SLC activity and the serum levels of adipokines, arguing against direct effects of GH on these measures. However, baseline values or changes in erythrocyte SLC activity, adiponectin, leptin, and IGFBP-1 correlated with glucose metabolism. This suggests that these factors are of importance for glucose homeostasis in GH-deficient adults, most likely through GH-independent mechanisms.