Background: In Mexican Americans, the IRS1 G972R polymorphism (rs1801278) has been associated to such a marked reduction in glomerular filtration rate (GFR) (i.e. β = -8.3 mL/min/1.73 m(2)) to be considered a major determinant of kidney function.
Methods: This was a cross-sectional study to investigate whether a similarly strong effect can also be observed among individuals of European ancestry. We investigated a total of 3973 White patients with type 2 diabetes. Standardized serum creatinine was measured by the modified kinetic Jaffè reaction and estimated GFR (eGFR) calculated by the modification diet renal disease (MDRD) formula; rs1801278 was genotyped by TaqMan assay.
Results: No significant association was observed, with R972 carriers showing only a modestly, not significant, lower eGFR level as compared with other subjects (β = -1.82 mL/min/1.73 m(2), P = 0.086).
Conclusions: Our data indicate that IRS1 G972R is not a strong determinant of GFR in diabetic patients of European ancestry as in Mexican Americans. Since we had 100% power to detect the previously reported association, the risk our finding is a false negative one is minimal.
Keywords: gene polymorphism; insulin-resistance; kidney dysfunction.