LAUSR

National Institutes of Health policy states that animal studies should account for sex as a biological variable by including males and females when possible. Male mice are mainly used in diabetes research involving mutations that inactivate the leptin hormone (Lep ob ) or its receptor (Lepr db ). We found that many metabolic phenotypes were similar in males and females from two C57BL/6J mutant strains with transient hyperglycemia (B6-ob and B6-db) and a C57BLKS/J strain with sustained hyperglycemia (BKS-db). In all strains, homozygous ob or db genotypes led to similar male and female weight gain despite sexual dimorphism in weights of control genotypes. In homozygous mutant mice at 8 and 16 weeks of age, the only significant weight differences between males and females were at 8 weeks in B6-db (males weighed 1.7 g more; P = 0.0037) and 16 weeks in B6-ob (females weighed 2.5 g more; P = 0.0017). BKS-db/db males had higher nonfasted blood glucose than females (415 mg/dL vs. 357 mg/dL; P Disclosure R.D. French: None. K. Leighton: None. J. Serrano: None. A. Schile: None.