Strength-duration curves and parameters related to excitability of control (), near-normoglycemic (), and hyperglycemic () groups. Stimulus intensity versus stimulus duration is illustrated in (a), and the two parameters related to excitability, rheobase and chronaxy, are shown in (b) and (c), respectively. The * symbol indicates statistical difference related to control (, ANOVA followed by Holm-Sidak comparisons test), and # symbol indicates statistical difference between curves (, two-way ANOVA followed by Holm-Sidak multiple comparison test).