SCD mice had lower fasting insulin levels than sex-matched WT and SCT mice at 0 minutes (Fig. 4B and 4D), correlating with the above findings (Fig. 3A and 3B), but had comparable insulin levels at 15 and 30 minutes into the IPGTT (Fig. 4B and 4D). This evidence concerns the gene INS and Schnyder corneal dystrophy.