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Murphy MJ, Metcalf BS, Voss LD, et al: Girls at five are intrinsically more insulin resistant than boys: the programming hypotheses revisited-the early bird study (Early Bird 6). Pediatrics 2004;113(1):82-86.
This study suggests that sex-linked genes may explain the reason girls are more insulin resistant than boys. Using anthropometry, physical activity, resting energy expenditures, and fasting glucose and insulin concentrations, the authors evaluated 307 healthy children (137 girls and 170 boys) at age 5 as the children entered primary school. Mean weights were similar, but girls showed greater body mass index and carried more subcutaneous fat.
Insulin resistance was 34.6% greater in girls than boys. Fasting concentrations of insulin and triglycerides were higher in girls. The girls had lower concentrations of high-density lipoprotein cholesterol and sex hormone-binding globulin. The results suggest that 5-year-old girls are more insulin resistant than boys because of possible gestational, genetic, or metabolic programming. New genome-wide searches for type II diabetes-susceptible genes have identified a region on the X chromosome linked to diabetes and impaired glucose tolerance.