In Reply: Dr Saad and colleagues draw attention to the possibility that genetic factors that influence insulin-mediated fetal growth, affecting birth weight and insulin resistance, could underlie the birth weight–type 2 diabetes association. We agree that genetic factors could be important but consider it unlikely that a single gene polymorphism would account for the observed complex, population-wide associations. Several genetic variants with moderate effects, interacting with environmental influences, would probably be necessary.
Whincup PH, Owen CG, Cook DG. Birth Weight and Type 2 Diabetes in Adults—Reply. JAMA. 2009;301(15):1539-1541. doi:10.1001/jama.2009.487