INSR and Insulin resistance: Although the overexpression of IR A (i.e., the IR isoform without the exon 11-encoded sequence) has been reported in one T2DM case with extreme insulin resistance and hyperinsulinemia (Norgren et al., 1994), a decrease in the IR A form has been more frequently reported in T2DM (Mosthaf et al., 1991; Sesti et al., 1991; Kellerer et al., 1993; Norgren et al., 1993).