Measures of glucose homeostasis in GH−/− mice. (A) Fasting blood glucose and (B) fasting serum insulin levels at age 6 mo (n = 8 to 11). GTTs in (C) males and (D) females at age 5 mo (n = 8 to 11). ITTs in (E) males and (F) females at age 5.5 mo (n = 8 to 11). Mean pancreatic islet cell size is shown for (G) males and (J) females. (H, I, K, L) Representative histological images. Hematoxylin and eosin–stained pancreatic islets are shown at ×20 magnification. Scale bars, 100 μm. Vertical bars represent standard error. *P < 0.05, significantly different from WT controls.