Type 2 diabetes mellitus (T2DM) is one of many disorders where genetic variation determines disease susceptibility. As gene variation is linked to native environment and social behavior, studies on lab animals are limited by artificial influences on diet and breeding. Thus, Roxanne Oriel and colleagues examined T2DM in two genetically similar species of field mice (Peromyscus) that differ in native environment and behavior. They show that males of one species have both low stress hormone levels and stress-induced blood sugar increases not seen in a notably calmer species, or in females. In addition to tests using consomic mice, their data suggests that stress-induced blood sugar elevation is the result of Y-chromosome-linked genetic variance. Their work demonstrates the importance of behavior and environmental background in studying genetic variation and diabetes risk.

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