ADIPOR2 and diabetes mellitus: This is interesting because the AdipoR2 knockout mice are reported to have a more severe phenotype, including an enlarged brain, male sterility, low weight, and increased risk of diabetes (5, 35), than the AdipoR1 mice, which primarily show a retina defect that is also found in humans with mutations in AdipoR1 (7, 8, 36, 37), as well as a tendency to gain weight (5).