Figure 1: Glutamate was increased in the plasma of diabetics in vivo and in the supernatant of RINm5f cells exposed to high glucose in vitro.

(a) The concentration of glutamate in the plasma of normal or diabetic patients (*p < 0.05 vs Normal). (b) The concentration of glutamate in the plasma of control or diabetic mice (n = 14, *p < 0.05 vs Control). (c) The concentration of glutamate in the supernatant of cultured RINm5f β-cells treated with 33.3 mM glucose for 72 h and/or GDH (20 unit/mL) (n = 5, *p < 0.05 vs control, #p < 0.05 vs HG). (d) Effect of GDH (20 unit/mL) treatment for 72 h on the cell viability of RINm5f β-cells (n = 9). (e) Effect of GDH treatment on insulin secretion from RINm5f β-cells incubated with 33.3 mM glucose for 72 h (n = 5, *p < 0.05 vs control, #p < 0.05 vs HG).