Objective: Glomerular hyperfiltration may predict diabetic nephropathy in type 1 diabetes, and some studies suggest that the ACE D allele is associated with diabetic nephropathy. The aim of this study was to examine a possible relationship between glomerular hyperfiltration and ACE insertion/deletion (I/D) polymorphism in type 1 diabetic children and adolescents.
Research design and methods: A cross-sectional study was conducted to examine the relationship between glomerular hyperfiltration and ACE (I/D) polymorphism in 76 type 1 diabetic children and adolescents without diabetic nephropathy (mean +/- SD: age 16 +/- 3 years; diabetes duration 7 +/- 4 years; age at diabetes onset 9 +/- 4 years; HbA1c 9.5 +/- 1.9%). Glomerular hyperfiltration (defined as a glomerular filtration rate [GFR] > or = 135 ml.min-1. 1.73 m-2 and by 51Cr-labeled EDTA plasma disappearance technique) and ACE I/D genotypes and plasma levels (enzyme-linked immunosorbent assay [ELISA] method) were determined.
Results: Of the patients, 29 (38%) displayed glomerular hyperfiltration. An association between glomerular hyperfiltration and ACE (I/D) polymorphism was observed (chi 2 = 7.09, P = 0.029) because of a reduced proportion of DD genotypes among patients with glomerular hyperfiltration (4 vs. 19; chi 2 = 6.03, P = 0.014) and not because of an excess of the II genotype (5 vs. 9; chi 2 = 0.04, P = 0.83). Age, diabetes duration, age at diabetes onset, and HbA1c were not different according to genotype. Patients with glomerular hyperfiltration had low plasma ACE levels, compared with those with normal glomerular filtration (457 +/- 157 vs. 553 +/- 186 micrograms/l; P = 0.027).
Conclusions: These results suggest an unexpected association between glomerular hyperfiltration and ACE (I/D) polymorphism, characterized by a defect of the DD genotype among type 1 diabetic children and adolescents with glomerular hyperfiltration.