Background: The XbaI polymorphism in the glucose transporter GLUT1 gene has been implicated in the development of diabetic nephropathy in Chinese type 2 diabetes patients.
Methods: To examine whether the XbaI polymorphism is involved in the development of diabetic nephropathy in Caucasian type 2 diabetes patients, a large case control study was performed. The study group of 444 patients with type 2 diabetes consisted of three subgroups: 162 patients with normoalbuminuria (only patients with duration of type 2 diabetes of at least 10 years after diagnosis); 150 with microalbuminuria; and 132 subjects with persistent proteinuria or chronic renal failure (CRF). The polymerase chain reaction (PCR)-based genotyping of the XbaI polymorphism was performed in each subject.
Results: The genotype distribution in the subgroups showed an increased frequency of the (+/+) genotype in patients with microalbuminuria (41%; OR 1.40, 95% CI, 0.89 to 2.24) and proteinuria/CRF (47%; OR 1.82, 95% CI, 1.13 to 2.93, P = 0.013) when compared with normoalbuminuria (33%). No difference in the genotype distribution was observed between type 2 diabetes patients and healthy controls.
Conclusions: The results of this study in Caucasian patients with type 2 diabetes indicate that the XbaI(-) allele in the GLUT1 gene protects against the development of diabetic nephropathy. Our results are in contrast to the case control study in Chinese patients with type 2 diabetes in which the presence of the XbaI(-) allele appeared to have a strong association with the development of diabetic nephropathy.